Classification of Lower Organisms (PDF)

The Classification of Lower Organisms  Ernst Hkinrich Haickei, in 1874 From Rolschc (1906). By permission of Macrae Smith Company.  C f3 The Classification of LOWER ORGANISMS By HER...

The Classification of Lower Organisms  Ernst Hkinrich Haickei, in 1874 From Rolschc (1906). By permission of Macrae Smith Company.  C f3 The Classification of LOWER ORGANISMS By HERBERT FAULKNER COPELAND \ PACIFIC ^,kfi^..^ ^., BOOKS PALO ALTO, CALIFORNIA  Copyright 1956 by Herbert F. Copeland Library of Congress Catalog Card Number 56-7944 Published by PACIFIC BOOKS Palo Alto, California Printed and bound in the United States of America  CONTENTS Chapter Page I. Introduction 1 II. An Essay on Nomenclature 6 III. Kingdom Mychota 12 Phylum Archezoa 17 Class 1. Schizophyta 18 Order 1. Schizosporea 18 Order 2. Actinomycetalea 24 Order 3. Caulobacterialea 25 Class 2. Myxoschizomycetes 27 Order 1. Myxobactralea 27 Order 2. Spirochaetalea 28 Class 3. Archiplastidea 29 Order 1. Rhodobacteria 31 Order 2. Sphaerotilalea 33 Order 3.Coccogonea 33 Order 4.Gloiophycea 33 IV. Kingdom Protoctista 37 V. Phylum Rhodophyta 40 Class 1. Bangialea 41 Order Bangiacea 41 Class Heterocarpea 2. 44 Order 1. Cryptospermea 47 Order 2. Sphaerococcoidea 47 Order 3. Gelidialea 49 Order 4. Furccllariea 50 Order 5. Coeloblastea 51 Order 6. Floridea 51 VI. Phylum Phaeophyta 53 Class 1. Heterokonta 55 Order 1. Ochromonadalea 57 Order 2. Silicoflagellata 61 Order 3. Vaucheriacea 63 Order 4. Choanoflagellata 67 Order 5. Hyphochytrialea 69 Class 2. Bacillariacea 69 Order 1. Disciformia 73 Order 2. Diatomea 74 Class 3. Oomycetes 76 Order 1. Saprolegnina 77 Order 2. Peronosporina 80 Order 3. Lagenidialea 81 Class 4. Melanophycea 82 Order 1 Phaeozoosporea. 86 Order 2. Sphacelarialea 86 Order 3. Dictyotea 86 Order 4. Sporochnoidea 87 V ly Chapter Page Orders. Cutlerialea 88 Order 6. Laminariea 89 Order 7. Fucoidea 91 VII. Phylum Pyrrhophyta 94 Class Mastigophora 95 Order 1. Cryptomonadalea 96 Order 2. Adiniferidea 98 Order 3. Cystoflagellata 99 Order 4. Cilioflagellata 102 Order Astoma 5. 105 VIII. Phylum Opisthokonta 110 Class Archimycetes Ill Order 1. Monoblepharidalea Ill Order 2. Chytridinea 113 IX. Phylum Inophyta 119 Class Zygomycetes 1. 121 Order 1. Mucorina 121 Order 2. Entomophthorinea 124 Class 2. Ascomycetes 125 Order 1. Endomycetalea 129 Order 2. Mucedines 130 Order 3. Perisporiacea 131 Order 4. Phacidialea 133 Order 5. Cupulata 134 Order 6. Exoascalea 137 Order 7. Sclerocarpa 137 Order 8. Laboulbenialea 140 Class3. Hyphomycetes 140 Order 1. Phomatalea.... 141 Order 2. Melanconialea 141 Order 3. Nematothecia 141 Class 4. Basidiomycetes 142 Order 1. Protobasidiomycetes 146 Order 2. Hypodermia 147 Order 3. Ustilaginea 149 Order 4. Tremcllina 149 Order 5. Dacryomycetalea 150 Order 6. Fungi 150 Order 7. Dermatocarpa 152 X. Phylum Protoplasta 157 Class 1. Zoomastigoda 157 Order 1. Rhizoflagellata 158 Order 2. Polymastigida 163 Order 3. Trichomonadina 166 Order 4. Hypcrmastiglna 168 Class 2. Mycetozoa 171 Order 1. Enteridiea 171 Order 2. Exosporea 177 vi Chapter Page Order 3. Phytomyxida 177 Class 3. Rhizopoda 179 Order 1. Monosomatia 183 Order 2. Miliolidea 185 Order 3. Foraminifera... 185 Order 4. Globigerinidea 187 Order 5. Nummulidnidea 188 Class 4. Heliozoa 189 Order 1. Radioflagellata 190 Order 2. Radiolaria 194 Order 3. Acantharia 195 Order 4. Monopylaria 198 Orders. Phaeosphaeria 198 Class 5. Sarkodina 200 Order 1. Nuda 201 Order 2. Lampramoebae 205 XI. Phylum Fungilli 206 Class 1. Sporozoa 207 Order 1. Oligosporea 209 Order 2. Polysporea 211 Order 3. Gymnosporidiida 211 Order 4. Dolichocystida 214 Orders. Schizogregarinida 215 Order 6. Monocystidea 215 Order 7. Polycystidea 216 Order 8. Haplosporidiidea 218 Class 2. Neosporidia 219 Order 1. Phaenocystes 219 Order 2. Actinomyxida 221 Order 3. Cryptocystes 222 XII. Phylum Ciliophora 223 Class 1. Infusoria 228 Order 1. Opalinalea 228 Order 2. Holotricha 229 Order 3. Heterotricha 230 Order 4. Hypotricha 233 Order 5. Stomatoda 233 Class 2. Tentaculifera 235 Order Suctoria 235 List of Nomenclatural Novelties 237 Bibliography 238 Index 271 VII  LIST OF ILLUSTRATIONS Portrait of Ernst Heinrich Haeckel Frontispiece Figure Page 1. Structure of cells of blue-green algae 13 2. Photographs of Escherichia coli... 15 3. Caulobacterialea; Myxobactralea; Cristispira Veneris 26 4. Coccogonea; Gloiophycea 32 5. Bangialea 42 6. Nuclear phenomena in Polysiphonia violacea 45 7. Heterocarpea 48 8. Ochromonadalea 54 9. Ochromonadalea; Silicoflagellata 56 10. Vaucheriacea 64 11. Choanoflagellata 68 12. Hyphochytrialea 70 13. Bacillariacea 72 14. Oomycetes 78 15. Stages of nuclear division in Stypocaulon 84 16. Familiar kelps of Pacific North America 90 17. Microscopic reproductive structures of Laminaria yezoensis... 92 18. Cryptomonadalea 97 19. Cystoflagellata; Cilioflagellata 104 20. Astoma 106 21. Astoma 108 22. Monoblepharidalea 114 23. Chytridinea 116 24. Zygomycetes 122 25. Ascomycetes 132 26. Ascomycetes 136 27. Mycosphaerella personata 138 28. Basidiomycetes 144 29. Fruits of Agaricacea 153 30. Rhizoflagellata 160 31. Polymastigida; Trichomonadina 164 32. Hypermastigina 170 33. Mycetozoa 176 34. Ceratiomyxafruticulosa 178 35. Life cycle of "Tretomphalus" i. e., Discorbis or Cymbalo por a... 180 36. Shells of Rhizopoda 184 37. Radioflagellata 192 38. Radiolaria; Acantharia; Monopylaria; Phaeosphaeria 196 39. Chaos Protheus 200 40. Sarkodina 204 41. Life cycle of Goussia Schuhergi 208 42. LUe cycle ofPlasmodium; Babesia bigemina 212 43. Life cycle of Myxoceros Blennius 220 44. Infusoria, order Hypotricha 232 45. Tokophrya Lemnarum 234 ix  Chapter I INTRODUCTION The purpose of this work is to persuade the community of biologists that the ac- cepted primary classification of living things as two kingdoms, plants and animals, should be abandoned; that the kingdoms of plants and animals are to be given definite limits,and that the organisms excluded from them are to be organized as two other kingdoms. The names of the additional kingdoms, as fixed by generally accepted principles of nomenclature, appear to be respectively Mychota and Protoctista. These ideas originated, so far as I am concerned, in the instruction of Edwin Bingham Copeland, my father, who, when I was scarcely of high school age, admitted me to his college course in elementary botany. He thought it right to teach freshmen the fundamental principles of classification. These include the following: The kinds of organisms constitute a system of groups; the groups and the system exist in nature, and are to be discovered by man, not devised or constructed. The system is of a definite and peculiar pattern. By every feature of this pattern, we are inductively convinced that the kinds of organisms, the groups, and the system are products of evolution. It is this system that is properly designated the natural system or the natural classification of organisms. It is only by metaphor or ellipsis that these terms can be applied to systems formulated by men and published in books. Men have developed a organisms which may be called the taxo- classification of nomic system. Its function —the purposewhich men have constructed it is to for — serve as an index to all that is known about organisms. This system is subject to cer- tain conventions which experience has shown to be expedient. Among natural groups, there are intergradations; taxonomic groups are conceived as sharply limited. Natural groups are not of definite grades; taxonomic groups are assigned to grades. When we say that Pisces and Filicineae are classes, we are expressing a fact of human conven- ience, not a fact of nature.The names assigned to groups are obviously conventional. Since the taxonomic system represents knowledge, and since knowledge is ad- vancing, this system is inherently subject to change. It is the right and duty of every person who thinks that the taxonomic system can be improved to propose to change it. A salutary convention requires that proposals in taxonomy be unequivocal: one proposes a change by publishing it as in effect; it comes actually into effect in the degree that the generality of students of classification accept it. The changes which are accepted are those which appear to make the taxonomic system, within its conven- tions, a better representation of the natural system. Different presentations of the taxonomic system are related to the natural system as pictures of a tree, by artists of different degrees of skill or of different schools, are related to the actual tree; the taxonomic system is a conventionalized representation of the natural system so far as the natural system known. is These statements are intended to make several points. First, as a personal matter, advancement of knowledge of natural classification, and corresponding improvement of the taxonomic system, have been my purpose during the greater part of a normal lifetime. Secondly, I have pursued this purpose, and continue to pursue it, under the guidance of principles which all students of classification will accept (perhaps with variations in the words in which they are stated). In the third place, I have tried to answer the question which scientists other than students of classification, and likewise the laity, are always asking us: why can one not leave accepted classification undis- 2 ] The Classification of Lower Organisms turbed? One proposes changes in order to express what one supposes to be improved knowledge of the kinds of organisms which belong together as facts of nature. If here I place bacteria in a different kingdom from plants, and Infusoria in a different king- dom from animals, it is because I believe that everyone will have a better understand- ing of each of these four groups if he does not think of any two of them as belonging to the same kingdom. The course of evolution believed to have produced those features of the natural system to which the present work gives taxonomic expression is next to be described. Life originated on this earth, by natural processes, under conditions other than those of the present, once only. These are the opinions of Oparin ( 1938) 1, and appear sound, although some of the details which he suggested may not be. When the crust of the earth first became cool, it was covered by an atmosphere of ammonia, water vapor, and methane, and by an ocean containing the gases in the atmosphere above it and minerals dissolved from the crust. This is to state the hypotheses that organic matter in the form of methane is older than life; and that whereas conditions on the face of the earth tend now to cause oxidation, they tended originally to cause reduc- tion. In a medium of the nature of the supposed primitive ocean, spontanous chemical changes will occur and produce organic compounds of considerable complexity: this has repeatedly been demonstrated by experiment. To convert a solution of ammonia, methane, and minerals into protoplasm, Oparin postulates a very long series of changes, producing successively more complicated compounds and mixtures, and re- quiring perhaps hundreds of millions of years. The changes are conceived as acci- dents; they are supposed to have been probable accidents, like throwing a seven at dice, not events which could only very rarely occur by accident, like throwing twenty sevens in succession. By supposing that some of these processes used up the m.aterials neces- sary for them, Oparin provides an explanation of the single origin of life: we are confident that all life is of one origin, because all protoplasm is of the same general nature, and all life consists of essentially the same processes. The course of events described would have yielded, as the original form of life, anaerobic saprophytes; this is in harmony with the fact that anaerobic energesis is in a sense the basic metabolic process. The would scarcely have possessed nuclei: Oparin's original organisms theories indicate, as the most primitive form of life which has been able to survive, the anaerobic bacteria. The anaerobic bacteria are indeed very far removed from any lifeless things; their protoplasm and their metabolism are fundamentally the same as ours. Life requires energy. Under anaerobic conditions, an organism can obtain energy by converting sugars to alcohol, but it can not use alcohol as a source of energy. This example means that anaerobic energesis yields energy in strictly limited quantity and produces incompletely oxidized compounds. So long as all life was anaerobic, it was engaged in converting the organic matter upon which it depended into forms which it could not use; life under these conditions, at least if they persisted for any great period of time, was surely very sluggish. A further scries of changes in the metabolic system, occurring accidentally in certain organisms and preserved by natural selec- tion, brought photosynthesis into existence. The purple bacteria are believed to rep- resent stages in the evolution of photosynthesis, which exists in its fully developed form, involving the release of elemental oxygen, in the blue-green algae. Once photo- ^ Dates in parentheses are references to works which have been consulted and listed in the bibliography.  Introduction [ 3 synthesis was established in certain organisms, aerobic energesis became possible both to these and to others. This made possible a manner of life more vigorously active — than before. The inconsiderable groups of autotrophic bacteria the organisms which live by oxidizing inorganic matter — appear to be secondary developments dependent upon the existence of photosynthesis. — The organisms whose origin has been suggested thus far the ordinary bacteria, anaerobic and aerobic, the autotrophic bacteria, the purple bacteria, and the blue- — green algae are relatively simple in structure and function; all consist of minute physiologically independent cells. The first step in the evolution of more complex organisms was the evolution of the nucleus. Morphologically, the nucleus is a part of a protoplast which is set apart by a mem- brane and which originates ordinarily by division of a pre-existent nucleus in the manner called mitosis. In this process, a definite number of definite chromosomes appear and undergo equal division. The nucleus exercises control over the protoplast in which it lies. Its controlling action depends upon the chromosomes which go into it, and mitosis has the effect that all nuclei which are derived from one original nu- cleus strictly by normal processes of mitosis are identical in the controlling effects which they exert. Thus the nucleus serves for the precise transmission of a compli- — cated heredity. Beside mitosis, there are two other processes two only meiosis and — karyogamy, by which nuclei may produce other normal and enduringly viable nuclei. In a sequence of generations of individuals sexually produced, these processes occur alternately, each one at one point in each cycle of sexual i-eproductlon. Mendelian heredity is produced by changes, in the sets of chromosomes (or parts of chromo- somes) in individual nuclei, which occur during meiosis and karyogamy. The role of the nucleus in sexual reproduction is one of its essential characters: the nucleus is re- lated to sexual reproduction, including Mendelian heredity, as structure to function. The existence of organisms without nuclei shows that the nucleus evolved after life did: it did not evolve at the same time as protoplasm. The essential uniformity of the nucleus and of its association with sexual reproduction shows that these things evolved only once, and together. There are a very few organisms, as Porphyridium and Prasiola, in which the presence or absence of nuclei is not certain; there is ac- cordingly scant evidence for speculation as to the manner of this evolution. As to the tim.e, we know only that microfossils representing nucleate organisms occur in the uppermost strata of the Proterozoic era. By making possible the precise transmission of a complicated heredity, the nucleus has made possible the development of complexities of structure and function exceed- ing by far anything occurring in non-nucleate organisms. It appears that as soon as the nucleus was in existence, organisms provided with it entered upon evolution in many characters and gave rise to many distinguishable groups. Among these groups, those which consist respectively of the typical plants and the typical animals are the greatest. There however, neither any a priori reason, nor any evidence from nature, is, for a belief that all groups of nucleate organisms must naturally belong to one or the other of these two. Several other groups, in general much less considerable than these, are thoroughly distinct and appear equally ancient. E. B. Copeland understood the history of life very much as it has just been pre- sented. In his teaching, he treated the bacteria and blue-green algae as standing en- tirely apart both from plants and from animals, and pointed out several other groups which are not as a matter of nature either plants or animals. It was his opinion that these groups should be treated as a series of minor kingdoms; he excused himself 4 ] The Classification of Lower Organisms from the attempt to formulate a definite and comprehensive system. This teaching was the original stimulus which has led to the present work. I bear witness that E. B. Copeland taught these things in 1914; he did not publish them until he had ceased to teach (1927). In the year 1926, when the teaching of elementary botany was first fully my own responsibility, I came to the conclusion that the establishment of several kingdoms of nucleate organisms in addition to plants and animals is not feasible; that all of these organisms are to be treated as one kingdom. This is one of the few points of originality which I claim for my work. It is true that the kingdom thus described is not very different from the third kingdom which various early authors proposed and which Haeckel (1866) named Protista. Haeckel, however, in his varied presentations of the kingdom Protista, included always the bacteria. By setting apart the bacteria and blue-green algae as yet another kingdom, one meets, at least in part, the objection to the "third kingdom" that it is heterogeneous beyond what can be tolerated. It has been necessary to meet also the objection that the "third kingdom" substi- tutes, for an acknowledgedly vague boundary between plants and animals, two vague boundaries: it has been necessary to recognize characters by which sharp definition can be given to plants and animals. It is my contention that these characters have long been known. The kingdom of plants, as the taxonomic representation of a natural group, is to be defined by the system of chloroplast pigments described by Willstatter and Stoll (1913), and also by the production of certain carbohydrates which occur only sporadically elsewhere. The kingdom of animals is defined by em- bryonic development through the stages called blastula and gastrula, as pointed out by Haeckel (1872). It is believed that no organisms exhibit both of these sets of characters; the "third kingdom" includes the nucleate organisms which exhibit neither. The kingdoms of plants and animals as here defined are essentially those which are traditionally and popularly accepted. They include all the creatures which Linnaeus listed as plants and animals, with the exceptions of forms of which he knew little, and which he listed superficially at the ends of his treatments of the respective kingdoms. Of kingdoms without ex- course, the definitions are not warranted to describe the ception. For one thing, each is have come into existence by evolution supposed to through a line of organisms which exhibited its characters imperfectly. For another, evolution can erase what it has created; it is proper to include in a group organisms which have by degeneration lost its formal characters. These things are true of all taxonomic groups. In due form, then, the system of kingdoms here maintained is as follows: Kingdom I. Mychota. Organisms without nuclei; the bacteria and blue-green algae. Kingdom II. Protoctista. Nucleate organisms not of the characters of plants and animals; the protozoa, the red and brown algae, and the fungi. Kingdom III. Plantae. Organisms inoccur chloroplasts, being plastids whose cells of a bright green color, containing the pigments chlorophyll a, chlorophyll h, carotin, and xanthophyll, and no others; and which produce sucrose, true starch, and true cellulose. Kingdom IV. Animalia. Multicellular organisms which pass during development through the stages called blastula and gastrula; typically predatory, and accordingly consisting of unwalled cells and attaining high complexity of structure and function. This system has twice been given brief publication (1938, 1947). I am glad to say  Introduction [ 5 that Barkley (1939, 1949) and Rothmaler (1948) maintain a system of kingdoms which differs from this in a single significant detail. Assuming that this system is tenable as a matter of reason, it will nevertheless not be accepted among taxonomists unless they have some knowledge of what it means in detail. No person is called upon to recognize the kingdoms Mychota and Protoc- tista until systems of their subordinate groups are available. The bulk of the present work consists of such systems. Complete systems of divisions or phyla, classes, and orders are presented. Groups of lower rank are presented in part, as examples. As a matter of facility, the groups of lower rank are presented more fully in the smaller or better known groups than in the larger or more obscure. The preparation of this work has taken more than ten years. In the course of it I have received much help. Among those who have answered queries, or who have in various drafts scrutinized the whole work or parts of it for faults of every degree of significance, are Dr. G. M. Smith of Stanford University; Dr. A. S. Campbell of St. Mary's College; Dr. Herbert Graham, formerly of Mills College; Dr. Lee Bonar, Dr. G. L. Papenfuss, and Dr. H. L. Mason of the University of California at Berkeley; Dr. E. R. Noble of the University of California at Santa Barbara; and Dr. H. C. Day of Sacramento Junior College. The counsel of E. B. Copeland has not been withheld. It is a matter of grief that two distinguished zoologists of the University of California, Dr. S. F. Light and Dr. Harold Kirby, have passed away during the long course of this work; as have two colleagues who were my closest friends, Dr. H. J. Child and Dr. C. C. Wright. The portrait of Haeckel which is my frontispiece is used by permission of Macrae Smith Company, Philadelphia. Two figures of Chrysocapsa are used by permission of the Cambridge University Press. Numerous figures have been taken from the Archiv filr Protistenkunde with the gracious permission of Prof. Dr. Max Hartmann. We do well to realize our indebtedness to libraries and librarians. To a great extent, this work has been made possible by the unstinted hospitality of the Biology Library of the University of California at Berkeley. Two statements appear regularly in prefaces; they are of truths which are strongly impressed upon authors. In the first place, those who have given help have made the work better; the author alone is responsible for deficiencies. The foregoing list of good friends and good scholars does not claim them as proponents of the thesis of this work. In the second place, the work is not offered as perfect or nearly so. The scholar in a strictly limited field may become master of the available knowledge. One who at- tempts studies in a broad field realizes that he is dealing with many subjects of which others know far more than he; that he has not wrung dry the existing literature; that some of the problems which puzzle him will be solved if he will wait a little longer. His colleagues have a right to raise these matters as criticisms. But surely, it is not desired that studies in broad fields be never attempted or indefinitely delayed. A matter which is particularly likely to arouse criticism is that of the names which are here applied to the groups. The principles according to which this has been done are set forth in the following chapter. I beg my colleagues, in dealing with this chapter and with the names subsequently applied, not to imagine that I have acted without grave thought. I have decided, that as in classification, so also in nomenclature, I should set before the community of biologists an experiment in the application of principles; among which principles there are surely some whose strict application will be to the good of our science.  Chapter II AN ESSAY ON NOMENCLATURE Whoever sets fortha system of groups finds himself under the necessity of making responsible decisions as to names. The kingdoms have received more names than one (Table 1 ), and so have nearly all of the major groups within them: it has here been necessary to decide as to the validity and application of the names Flagellata and Mastigophora, Rhodophyceae and Florideae, Rhizopoda and Sarcodina, and many others. TABLE 1. Names Applied by Various Authors to the Kingdoms OF Systems of Four Kingdoms Authors Kingdoms  An Essay on Nomenclature [ 7 The bacteriological code most part a condensation of an earlier edition is for the of the botanical code. It includes the that the name of a genus of bacteria odd feature is to be changed if it had previously been used either among plants or among Protozoa. Since there is an earlier Phytomonas among flagellates, bacteriologists have given a new name to the bacterium Phytomonas. The avoidance of homonyms which they desire will not, however, be attained: no zoologist will allow a new name for the flagellate Klebsiella on account of an earlier Klebsiella among bacteria. The grounds upon which these things are treated as wrong are provided by a passage in the botanical laws of 1867 which is believed to define the legitimate authority of congresses and codes: "Les regies de la nomenclature ne pouvent etre ni arbitraires ni imposees. Elles doivent etre bassees sur des motifs assez clairs et assez forts pour que chacun les comprenne et soit dispose a les accepter." implied by this statement that principles, appealing to the reason and found It is sound by the trial of experience, were in existence when it was written; and this is the truth. By this statement, the legitimate powers of congresses are those of courts of common law, which avoid the explicit making of law, but discover the law, inter- pret it, and apply it. Congresses and codes may legitimately (a) state explicitly corollaries of the principles when they are not obvious; and (b) determine arbitrarily matters which are necessarily determined arbitrarily, not being within the range of principle. One would not in theory deny a power (c) to validate breaches of principle when these are of an expedience verging on necessity; but its use by botanical con- gresses to produce a roll of exceptions of twice the bulk of the text of the code leads one doubt the expedience of this admission. It has been through failure to recog- to nize the legitimate limits of their powers — through a conception that their powers are sovereign or plenary — that international congresses have come to enact codes conflicting with each other and giving incomplete satisfaction in themselves. Under these circumstances, a nomenclature of superior legitimacy can be applied in groups treated as removed from the jurisdiction of the codes. Not without diffi- dence, this assumption is extended to the bacteria; it will be agreed that the nomen- clatural practice applied to the bacteria must be the same as that which is applied to the blue-green algae. Here one attempts a brief formulation of those principles, appealing to reason and proven sound in practice, to which all nomenclature must conform. 1. Scientific names are words of the Latin language. They are not "of Latin form" or "construed as Latin"; they are Latin. This is to treat Latin as a living language and scientific names as subject to the rules of its grammar. They are not code-designa- tions, nor words of any language or none, as chemical names are. 2. The name of a group of the kind called a genus is a proper noun in the singular. Linnaeus replaced all generic names which were adjectives; all of us his successors should do likewise. 3. The names of groups of genera are proper nouns, or adjectives used as proper nouns, in the plural. The foregoing principles are of pre-Linnaean origin; beginning with his first sig- nificant work (1735), Linnaeus took them For the principle next to be for granted. stated, authority is the practice of Linnaeus in later works (1753 and subsequently) 4. The name of a species consists of the name of the genus to which it belongs fol- lowed by one epithet, ordinarily an adjective, occasionally a noun in apposition or in the genitive. 8 ] The Classification of Lower Organisms A fifth principle represents Linnaean practices as subsequently modified: 5. Named taxonomic groups are necessarily of certain fixed ranks called categories, There are seven principal categories, specified as follows. Every individual i.e., lists. organism belongs to a group conceived as the single kind and called a species. Every species belongs to a genus; every genus to a family; every family to an order; every order to a class; every class to a division or phylum; ever)' division or phylum to a kingdom. These conventions have the effect that the groups of each principal category embrace the entire range of the kinds of organisms. The categories of genera and species come down from classic antiquity. Linnaeus originated orders; he originated classes in the sense of named definite groups; and it appears that he is responsible for kingdoms: the writer knows of no earlier authority for the traditional three kingdoms of nature. The category next below that of king- doms has been variously called; originally it was emhranchements (Cuvier, 1812). The history of the category of families is somewhat involved. It originated in the work of Adanson (1763); in the following year, Linnaeus (1764) treated the groups which Adanson had called families as natural orders. Botanists for a long time held that families and orders are the same thing. Zoological practice gradually made fam- ilies a separate category. Authority for the list of seven principal categories as given is Agassiz (1857). Nothing prevents the assignment of groups to categories other than these, to sub- and the like. These may be called subordinate categories. The groups classes, tribes, of any subordinate category embrace only fragments of the range of kinds of organisms. The work of Linnaeus was largely innovation, and he did not have the face to de- clare binding the generally accepted rule of priority. Definite authority for the rule isde Candolle (1813). As currently applied, it may be stated as follows: 6. The valid name of a group is its oldest published name, conforming to the rules, and not previously applied in the same kingdom. As corollaries of the rule of priority, when groups are combined, the oldest name of any of them must be applied to the whole, and when a group is divided, its name must be retained for one of the parts. The part to which the original name is to be applied is determined by the method of types, formulated by Strickland and his as- sociates (1843) : 7. When is divided, its name must be applied to the portion which includes a group whatever part of it the original author would have regarded as typical. The part thus specified is the nomcnclatural type of the group. In the application of these principles to the naming of the groups of Mychota and Protoctista, the following practices appear expedient. A name is applied by publication in such fashion that the community of biologists may reasonably be held responsible for knowing of its existence and recognizing the entity to which it is to be applied. This means that it is to be printed in a technical book or journal and defined in a language for which the generality of biologists will not require an interpreter, namely Latin, English, French, or German. Any regulation more detailed than this is an excuse for breaches of priority. Definition is not neces- sarily by description: nearly all of the Linnaean genera of plants were established by the listing of species in the Species Plantarum. When two or more groups published in the same work at the same time are to be combined, their names are of equal priority. The choice of one of their names by the first author who combines them is binding.  An Essay on Nomenclature [ 9 A type as specified in the original publication of a group, or as implied by the in- clusion of a single subordinate group, is unchangeable. Linnaeus and his immediate successors had no conception of the device of types, and it is practically impossible to be certain of the elements which they would have regarded as typical in some of their groups. It remains necessary that the type system be applied to these groups. In some of them, it may be expedient that international authority, proceeding with due An individual scholar will do better to call what he caution, declare types arbitrarily. supposes to be the type of a group by a difTerent term, namely standard (Sprague, 1926) the standard of a group is a supposed type which remains open to debate. The : framers of codes have undertaken to make binding the choice of a type by the first author who divides a group. On various occasions, however, this action has been demonstrably mistaken. Certain venerable names, as Vermes and Algae as used by Linnaeus, were applied organisms among which the selection of a to altogether miscellaneous collections of standard would be purely arbitrary. Such names are called nomina confusa, and are to be abandoned. from the principle of the binomial nomenclature of species that no genus It follows is named one or more of its species are designated by binomial names. It fol- until lows also that in works in which the nomenclature of species is not definitely binomial no names are of any standing. Hence, the point of time from which priority is effective is that of the introduction of binomial nomenclature, namely 1753. The enactment of other starting points for the nomenclature of particular groups is pretended law which is not law, like the pretended laws of American states which attempt to regu- late interstate commerce under the appearance of doing something else. The original spelling of names, so far as it is tolerable Latin, is not to be changed. Errors of gender or number, obvious mistakes of spelling, and misprints, are to be corrected. Good Latin is written without diacritical marks: a German Umlaut in a name as published is corrected by inserting an e; accents, cedilles, and other barbar- isms are dropped. The codes err in prescribing changes in spelling beyond those which are here admitted. If they should establish uniformity in the future, it would be at the expense of divergence from the most respected works of the past. Specific epithets are capitalized if 1 names in the nominative, in ap- they are ( ) position with the generic names; (2) names of persons, places, or organisms in the genitive; (3) adjectives derived fromnames of persons. Transfer of groups from one kingdom to another does not warrant any meddling with names. When a group is transferred from one kingdom to another, its valid name in the former — its oldest name not previously used in the kingdom in which it was originally published —has priority from the date of its original publication. Names Some are proper nouns; the of groups higher than genera are in the plural. remainder are adjectives used as proper nouns, agreeing in gender with the names of the kingdoms in which they are included; either expressing characters of the groups which they designate, or consisting of generic names modified by terminations signi- fying "resembling" or "of the group of." Plurals of generic names are not tenable (de Candolle, 1813) Ericae means the species of the genus Erica; it does not mean, : and can not be used to designate, the genus together with its allies. Names consisting of words other than generic names modified by terminations signifying "resembling" or "of the group of" are not tenable, because they are nonsense: the name Conifer- inae, applied by Engler to a class, is an adjective with an additional adjectival termi- nation superimposed.  — 10 ] The Classification of Lower Organisms A name once applied in any principal category may not be transferred to another, unless be of a form barred in the former and prescribed in the latter. The main it clause of this statement is a consequence of the rule of priority. The exception is a concession to the practice of using names with uniform endings in certain categories. Names of groups not of principal categories do not have priority as against names applied in principal categories. This practice, which denies to names in subordinate categories the full sanction of priority, by the fact that groups in these cate- is justified which they occur; one is not gories are of concern only to specialists in the groups in in reason responsible for being aware of their names in groups outside of ones own specialty. Almost all had names with the uniform ending -aceae from families of plants have the point of time at which the category of families was distinguished from that of orders. Such names were applied to algae, liverworts, and mosses by Rabenhorst (1863) and to higher plants by Braun (in Ascherson, 1864). They are adjectives in the feminine, agreeing with the name of the kingdom Plantae. It is altogether expe- dient that names of this form be held obligatory throughout the kingdom of plants. A uniform termination for names of families of animals has been in use for many years, but these names are not equally positively sound both grammatically and by priority. There has been a strong tendency to apply uniform terminations to the names of groups of other categories. So far as concerns groups of subordinate categories suborders, subfamilies, and so forth — this practice appears expedient; these groups being of concern only to experts in the groups in which they occur, it is as well that their designations be of the nature of code designations rather than names. In at- tempting to put this practice into effect, some zoologists have made the mistake of applying the same adjective in different genders to different groups; they have not realized that Amoebida is the same word as Amoebidae. Meanwhile, uniform termi- nations for names of phyla, classes, and orders, beside involving wholesale violation of priority, is something of an insult to the intelligence. The terminations of ordinal names in -ales and of family names in -aceae, currently in use among the Mychota, are here changed to -alea and -acea to agree with the neuter name of the kingdom. A change of the gender of an adjective does not create a new word, and the original authorities for the names will stand. Accordingly: The name of an order of Mychota, if based on that of a genus, must bear the termi- nation -alea. Names of this form are valid in no other category of this kingdom, and may be reapplied to orders. They have priority and authority by publication explicitly as orders. Such names do not supersede older ordinal names not based on names of genera. The name Mychota is formed of the stem of a generic name (not of a family of necessarily a valid name, but never a later homonym) by adding the termination -acea. Names of this form are not valid in any other categor)', and may be reapplied to families. They have priority and authority by publication explicitly as families. The names of families of Protoctista, unlike those of Mychota, of plants, and of animals, do not have by priority prevalently a uniform termination. Many of the oldest were first named in -ina. Those of flagellates and myxomycetes have double sets of names, respectively in -aceae and -idae, in current use. It is not expedient to impose uniform terminations on the names of these groups, at least not in the present work. Accordingly: Each group of Protoctista is called by its oldest name of tenable form in the cor- rect category, barring any previously used in other principal categories, irrespective  An Essay on Nomenclature [ 1 of termination. All names which are adjectives are used in the neuter, but ascribed to the original authors. The practices described have resulted in the use of many names which will seem strange, producing lists which are undeniably heterogeneous. A friendly critic notes as an example of these things the Hst of classes, Heterokonta, Bacillariacea, Oomy- cetes, and Melanophycea, on page 55. It will be realized that the three among these names which are adjectives must be in the feminine if the groups are construed as Plantae, neuter if Protoctista. Taking this fact into account, these are actually the first names, not previously used in other principal categories, applied to these groups as classes. What other names could one use? Everyone will know what groups are intended. Would any person understand them better if new names had been created by applying a uniform termination to the old roots? Enough about nomenclature. We should begin to deal with organisms.  Chapter III KINGDOM MYCHOTA Kingdom I. MYCHOTA Enderlein Stamm Moneres Haeckel Gen. Morph. 2: xxii 1866), in part. ( ScHizoPHYTAE Cohn in Beitr. Biol. Pfl. 1, Heft 3: 201 (1875). Class ScHizoPHYTA or Protophyta McNab in Jour, of Bot. 15 340 ( 1877 ) not sec- : ; tion Protophyta nor cohors Protophyta Endlicher (1836). Kingdoms Protophyta and Protozoa Haeckel Syst. Phylog. 1: 90 (1894), in part; not Protophyta Endlicher nor class Protozoa Goldfuss (1818). Subdivision Schizophyta Engler in Engler and Prantl Nat. Pflanzenfam. I Teil, Abt. la: iii (1900). Division Schizophyta Wettstein Handb. Syst. Bot. 1 : 56 ( 1901 ). Phylum Protophyta Schaffner in Ohio Naturalist 9: 446 (1909), in part. Kingdom Mychota Enderlein Bakt.-Cyclog. 236 (1925). Kingdom Monera Copeland f. in Quart. Rev. Biol. 13: 385 (1938). Kingdom Anucleobionta Rothmaler in Biol. Zentralbl. 67: 248 (1948). Organisms without nuclei. The common name of Mychota in general is bacteria, but those which contain chlorophyll together with other pigments which make the green color impure are called blue-green algae. The cells of Mychota are always separate or physiologically independent: multi- cellular bodies with distinct tissues do not occur. The cells are of various shapes; most often they are cylindrical, being of diameters from a fraction of one micron to a few microns, rarely more. Except in the groups of myxobacteria and spirochaets, they are walled; the thickness of the walls is of the order of 0.02^ (Knasyi, 1944). The walls may compounds of slightly contain cellulose, but consist chiefly of pectates, oxidized polysaccharides with sulfate, calcium, and magnesium (Kylin, 1943). These compounds are readily rendered gelatinous by hydration or hydrolysis, and the cells are often imbedded in gelatinous layers called sheaths or capsules. In describing the Mychota as lacking nuclei, one commits himself to one side of a controversy of many years duration. Because of the greater size of the cells of the blue-green algae, the facts are more easily ascertained in this group than in the proper bacteria. The blue-green algae (Gardner, 1906; Swellengrebel, 1910; Haupt, 1923) cells of are divided into outer and inner parts which are not sharply distinct. Pigments occur in a dissolved or colloidal condition in the outer part, which contains also granules of stored food. The granules are not carbohydrate, although a form of glycogen dis- tinctfrom that of higher organisms has been extracted (Gardner; Kylin, 1943). The inner part contains rods and granules, some of which stain like chromatin, while others ("red granules of Biitschli") are stained red by methylene blue. Cell division is by constriction. Olive (1904) interpreted the inner part of the cell as a nucleus continually in process of mitosis, and accordingly without a membrane. It is true that in series of disk-shaped cellsone may recognize series of corresponding granules. Where the cells are more and granules of the interior are divided elongate, the rods at random. Haupt expressed the impropriety of calling any part of these cells a nucleus.  Kingdom Mychota [13 Recent studies of typical bacteria by conventional microtechnical methods (Rob- inow, 1942, 1949; Tulasne and Vendrely, 1947) and by the electron microscope (Hil- lier, Mudd, and Smith, 1949) have made it possible to recognize the essential identity of the structure of their cells with those of the blue-green algae. The protoplast con- sists of outer and inner parts. The outer part, considered as a substance, may be called ectoplasm (Knasyi, 1930), and the inner, considered as a body, may be called the central body (Biitschli, 1890). The ectoplasm is very thin, occupying usually less than one fifth of the radius of the cell. The spiral bands which have often been seen % Bi^i Z# )ii-i'- Ss;.- "ji;-^ Irx ;i©\ ^-> 'l-i" V^.?.. fw.^,.'^» ; ^vWfe 4m Fig. 1.- — Structure of cells of blue-green algae, a, Symploca Muscorum after Gardner (1906). b, Oscillatoria Princeps after Olive (1904). C, Lyngbya sp. from a slide prepared by Dr. P. Maheshwari, x 1,000. d, Anabacna circinnalis after Haupt (1923) x 2,000. and which Swellengrebel ( 1906) mistook for a nucleus, are thick- in cells of bacteria, enings of the ectoplasm. Specific stains for nucleoprotein (chromatin), as Feulgen or Giemsa, usually color uniformly the entire central body. If the cells are exposed to hydrochloric acid, a part of the nucleoprotein, containing ribonucleic acid, dissolves. The remainder, containing desoxyribonucleic acid, persists in the form, basically, of a single fairly large granule in each cell. In rod-shaped bacteria, this granule appears usually to divide by constriction before the cell begins to divide, and may redivide, so that the cell may contain two dumb-bell shaped bodies. De Lamater and Hunter (1951) succeeded in a partial de-staining of the dumb-bell shaped bodies and inter- preted them as dividing nuclei containing centrosomes and definite numbers of chromosomes; typical chromosomes, however, are never as small as the bodies they describe, and are not imbedded in bodies of nucleoprotein from which they can be distinguished only by the most refined technique. Enderlein (1916) observed in rod- shaped bacteria series of granules of which some at least are identical with the dumb- 14 ] The Classification of Lower Organisms bell shaped bodies. He named these granules mychits. It might be held that the mychit is a chromosome, and the central body of bacteria a nucleus of a single chromosome, if it were not true that the blue-green algae contain comparable bodies of variable form and indefinite number. Many bacteria swim by means of flagella. The diameter of the flagella, as revealed by the electron microscope, is of the order of 0.02 Their positions and lengths were [J.. made known, before the invention of the electron microscope, by the technique of Loeffler (1889), which consists essentially of depositing upon them a heavy layer of tannic acid. By the absence or presence and arrangement of flagella, bacteria are classified as of four types: atrichous, without flagella; monotrichous, with one flagel- lum at one end; lophotrichous, with a tuft of flagella at one end; peritrichous, with flagella on the sides. Myxobacteria, spirochaets, and such blue-green algae as are sheathless filaments, are capable of bending movements (some spirochaets, observed with the electron microscope, are found also to have flagella at the ends of the cells). Spirochaets swim vigorously; in myxobacteria and blue-green algae, the bending movements are a mat- ter of slow writhing. Filaments and cells of blue-green algae are capable also of a moderately rapid gliding movement. The mechanism of this movement has been the subject of much speculation, reviewed by Burkholder ( 1934), but remains uncer- tain. The appearance of the movement is as though it were caused by local secretion of substances affecting surface tension. The normal reproduction of by constriction of the cells, each into two Mychota is equal daughter cells; whence the various names in schizo- (Greek axi^co, to split). Henrici (1928) studied the changes undergone by bacteria during multiplication. As the cells become numerous, decreasing the food supply and producing substances harmful to themselves, they begin to attain greater length before dividing. Subse- quently there is a gradual transition to enlarged and distorted forms called involution forms, which divide irregularly, cutting off minute fragments. These observations suggest the idea that the involution forms are the true normal forms of bacteria, the so-called normal forms being a temporary stage adapted to rapid multiplication under favorable conditions. In many rod-shaped bacteria, when conditions cease to be ideal, the protoplasts produce within themselves walled bodies of dehydrated protoplasm called spores (endospores). In general, each cell produces only one spore. No experiment has definitely shown how long these spores can remain alive; it is surely a matter of cen- turies, doubtfully of millenia. Lohnis and Smith (1916, 1923) observed of Azotobactcr that numbers of proto- plasts might escape from their walls and unite in a common mass, which they named the symplasm. The existence of this stage has never been confirmed by other authori- ties. If the symplasm exists, it is a device for achieving the effect which nucleate or- ganisms attain by sexual reproduction, that is, combination of the heredity of differ- ent lines of ancestry. Tliat Mychota can actually combine characters from different linos of ancestry was first demonstrated beyond question by Tatum and Ledcrberg (1947). They mixed cultures of pairs of varieties of Escherichia coli, differing in two or more physiological characters, and isolated from the mixtures races having characters de- rived from both components. Further Mork, reviewed by Ledcrberg and Tatum (1953), has abundantly demonstrated phenomena analogous to typical sexual reproduction.  Kingdom Myrhola [15 '9^ ^ V* % ^ ^ ^^ m^ W 9m w% #^., li.^ Fig. 2. — Photographs Robinow, reproduced by of Escherichia coli by Dr. C. F. Hillier, Mudd, and Smith (1949); left, show the ectoplasm, in which stained to there are thickenings which tend to be spiral; right, stained to show the large re- peatedly dividing granule in the central body. About x 2,000. By courtesy of Dr. Robinow and of the Society of.\merican Bacteriologists.  Kingdom Mychota [17 The metabolic systems of the Mychota are remarkably diverse. The most super- ficial list of physiological types would include the following: (a) anaerobic parasites and saprophytes; (b) facultatively aerobic parasites and saprophytes; (c) the vinegar bacteria, being apparently the only known organisms which, while requiring organic matter, are incapable of anaerobic energesis; (d) the autotrophic bacteria, the only organisms which maintain life by oxidation of inorganic matter; (e) organisms living by incomplete photosynthesis; and (f) organisms capable of typical photosynthesis. Geologically, the Mychota are ancient. Iron deposits and certain other formations believed to have been produced by them occur in Archeozoic rocks estimated as more than a billion years old. More than five thousand names have been applied to species of bacteria, but in the attempt to distinguish them, only about fifteen hundred are enumerated (Ber- gey'sManual, 6th ed., 1948). The species of blue-green algae are probably fewer than one thousand. The classification of this group is inescapably highly tentative. The morphology issimple and not highly varied; the physiological characters likewise appear simple, but are highly varied, including many which are not known in other groups. The antiquity of the Mychota makes it probable that many groups which appear to be- long together consist actually of parallel developments. The undoubted antiquity of the apparent main groups would lead one to place them in the category of divisions or phyla; but it is not expedient to make many divisions of a group of 2500 species: would produce too many divisions of this a single class or classes of a single order. The kingdom is accordingly treated as a single phylum, and its main divisions as classes. Phylum ARCHEZOA Haeckel Archephyta and Archezoa Haeckel Syst. Phylog. 1:90 (1894); not Phylum yhylB. Archephyta Haeckel (1866). Phylum Myxophyceae Bessey in Univ. Nebraska Studies 7: 279 (1907). Phyla Dimychota and Monomychota Enderlein Bakt.-Cyclog. 236 (1925). Bacteriophyta and Cyanophyta Steinecke (1931). Stamme Cyanophyta and Schizomycophyta Pascher in Beih. bot. Centralbl. 48, Abt. 2: 330 (1931). Divisions Cyanophyta and Schizomycetae Stanier and van Niel in Jour. Bact. 42: 464 (1941). Characters of the kingdom. Archezoa is Haeckel's name, at the point cited, for the bacteria. The name had been applied othervv^ise by Perty (1852), but not in a principal category. It will not be considered inappropriate, if it be remembered that the meaning of zoe is as much life as animal. The conventional division of the group into two classes, bacteria and blue-green algae, not perfectly natural. All of the recognized blue-green algae belong together; is but the recognized bacteria are a wide miscellany, some of them belonging with the blue-green algae. Here three classes are recognized. 1. Cells without internal pigment, heterotrophic or living by chemosynthesis; not usually pro- ducing filaments with prominent sheaths. 18 ] The Classification of Lower Organisms 2. Cells with firm walls, non-motile or motile by means of flagella Class 1. Schizophyta. 2. Cells with thin walls or none, motile by means of changes of shape, also some- times by flagella Class 2. Myxoschizomycetes. 1. Cells mostly with internal pigment, living by photosynthesis or chemosynthesis, exception- ally heterotrophic; often producing filaments with prominent sheaths Class 3. Archiplastidea. Class 1. SCHIZOPHYTA (Cohn) McNab Schizomycetes Nageli ex Caspary in Bot. Zeit. 15: 760 (1857). Class Schizophyta or Protophyta McNab in Jour, of Bot. 15: 340 (1877). Class Schizomycetes Winter in Rabenhorst Kryptog.-Fl. Deutschland 1, Abt, 1: 33 (1879). Class Schizomycetae SchafTncr in Ohio Naturalist 9: 447 (1909). Classes Holocyclomor pha and Hemicyclomorpha Enderlein Bakt.-Cyclog. 236 (1925). Dependent or chemosynthetic Mychota, with walled cells, without photosynthetic pigments and not producing sheathed filaments. This class includes as orders the typical bacteria and two minor groups. 1. Cells solitary or loosely gathered into clusters or filaments, spherical, rod-shaped, or spiral, not differentiated along the axis Order 1. Schizosporea. 1. Consisting of branched filaments not divided into cells Order 2. Actinomycetalea. 1. Cells attached by stalks, the attached and free ends differentiated Order 3. Caulobacterialea. Order 1. Schizosporea [Schizosporeae] Cohn in Hedwigia 11: 17 (1872). Order Schizomycetes (Nageli) McNab in Jour, of Bot. 15: 340 (1877). Order Eubacteria Schroter 1886. Order Haplobacteriacei Fischer in Jahrb. wiss. Bot. 27: 139 (1895). Orders Cephalotrichinae and Peritrichinae Orla-Jensen in Centralbl. Bkt. Abt. 2,22: 334,344 (1909). Order Eubacteriales Buchanan in Jour. Bact. 2: 162 (1917). Mychota whose cells in the typical condition are without internal pigment, walled, of the form of rods, spheres, or spirals, not differentiated along the axis. As this is a numerous group, likely with advancing knowledge to require division, it will be well to provide it with a nomenclatural standard, and to suggest as such Cohn's principal discovery among bacteria, namely Bacillus sublilis. These are the typical bacteria. As originally described by Leeuwcnhoeck (1677), they were taken to be a few kinds of "animacules" distinguished only by extremely small size. Only after many years were they shown to be numerous and varied, and highly important as causes of diseases and of other natural phenomena. The natural classification of the typical bacteria has been hard to discern. The characters by which groups can be distinguished include forms of cells and of clusters of cells; absence or presence and arrangement of flagella; non-formation or formation  Kingdom My c hot a [ 19 of endospores; metabolic products; and the peculiar character called Gram reaction. The method Gram, 1884, consists of staining successively of staining invented by with gentian violet and iodine. It gives an intense blue-black color. From some bac- teria, this color is washed out by alcohol; others retain it; the former are said to be Gram negative, the latter Gram positive. In practice one applies successively gentian violet, iodine, alcohol, and safranine, the last being a red dye whose function is to make the Gram negative bacteria visible. The substance stained by gentian violet plus iodine is believed to be lipoid, such as occurs in all cells. The Gram positive quality is believed to consist in a relatively low isoelectric point, a capacity, that is, to combine with anions in a relatively acid medium. This quality lies in the ectoplasm of the cells and disappears in aging cultures. The classification given in Bergey's Manual (1923, 1925, 1930, 1934, 1939, 1948) is accepted (at least among Americans) as standard. The following system of thirteen families is a moderate rearrangement of the Bergeyan system, with certain ideas or names from Enderlein (1917, 1925), Buchanan ( 1925), Pribram (1929) and Stanier andvanNiel (1941). 1. Gram positive, with exceptions many of which are intracellular parasites; atrichous or peritrichous. 2. Spheres dividing in more planes than one. 3. Gram positive Family 1. Micrococcacea. 3. Gram negative; intracellular patho- gens in animals Family 2. Neisseriacea. 2. Rods, or spheres dividing in one plane. 3. Not producing endospores. 4. Atrichous. 5. Not intracellular parasites.. Family 3. Corynebacteriacea. 5. Intracellular parasites Family 4. Rickettsiacea. 4. Peritrichous Family 5. Kurthiacea. 3. Producing endospores Family 6. Bacillacea. 1. Gram negative. 2. Atrichous or peritrichous, requiring com- paratively complicated organic food. 3. Not plant pathogens. 4. Not fixing nitrogen. Capable of growth on or- 5. dinary media Family 7. Achromobacteriacea. 5. Requiring special media; minute atrichous pathogens. Family 8. Pasteurellacea. 4. Fixing nitrogen Family 10. Azotobacteriacea. 3. Plant pathogens Family 9. Rhizobiacea. 2. Atrichous, monotrichous, or lophotrich- ous; the atrichous representatives, and many can survive with organic others, foods simpler than carbohydrates, or with none. 3. Mostly requiring at least carbo- hydrates Family 11. Spirillacea.  : 20 ] The Classification of Lower Organisms 3. Not requiring carbohydrates. 4. Oxidizing alcohol to acetic acid, and acetic acid to CO2 and H2O Family 12. Acetobacteriacea. 4. Not as above; many examples strictly autotrophic Family 13. Nitrobagteriacea. Family 1. Micrococcacea [Micrococcaceae] Pribram in Jour. Bact. 18: 370, 385 (1929). Family Coccaceae Zopf 1884; but the genus Coccus is a scale insect. Gram positive spheres producing packets or irregular masses. Micrococcus, saprophytic or parasitic, producing irregular masses of cells; the pathogenic species have been treated as a separate genus Staphylococcus. Sarcina, saprophytic or commensal spheres pro- ducing packets. Family 2. Neisseriacea [Neisseriaceae] Prevot ex Bergey et al. Manual ed. 5 278 : (1938). Family Neisseriacees Prevot in Ann. Sci. Nat. Bot. ser. 10, 15: 119 (1933). Obligate parasites, the Gram negative spherical cells occurring chiefly in pairs within leucocytes in the lesions of disease. Neisseria gonorrhoeae, the gonococcus; A^. ]Veich- selbaumii Trevisan {N. intracellularis, N. meningitidis, Auctt.), the meningococcus. Family 3. Corynebacteriacea [Corynebacteriaceae] Lehmann and Neumann 1907. Family Corynebacteriidae Enderlein in Sitzber. Gess. naturf. Freunde Berlin (1917) 314. Family Lactobacillaceae Winslow et al. in Jour. Bact. 2: 561 (1917). Family Lactobacteriaceae Orla-Jensen 1921. Family Leptotrichaceae Pribram in Jour. Bact. 18: 372 (1929), not family Leptotrichacei Schroter 1886. Gram positive rods, or spheres dividing in one plane and producing chains, non-motile. Streptococcus, spheres in chains; saprophytes in milk, involved in the making of butter and cheese; and commensals and serious pathogens causing, for example, abscesses, septicemia, erysipelas,and pneumonia. Diplococcus, spheres usually in pairs, encapsulated. D. pneumoniae occurs in many immunologically distinct races which are the usual causes of pneumonia. Lactobacillus, rods, microaerophilic, producing lactic acid. In milk, involved in the making and cheese; in the oral cavity, being the usual agent of dental of butter caries (Rosebury, Linton, and Buchbinder, 1929); common in sewage. Leptotrichia, rods which become exceptionally long before dividing. Oral cavity of man and beasts. Corynebacterium, rods, becoming club-shaped, staining in a banded pattern. The type species is the agent of diphtheria, C. diphthcriae; the genus includes also many harmless commensals important only as making diagnosis difficult. The cells divide in an exceptional fashion, by breaking violently from one side to the other near one end; the cut-off end swings around beside the main body and proceeds to grow. Repeated division in this manner produces clusters of parallel cells (Park, \V'iliiams, and Krumweide, 1924). Family 4. Rickettsiacea [Rickettsiaceae] Pinkerton 1936. Families Bartonellaceae Gieszszykiewicz 1939 and Chlamydozoaceae Moshkovsky 1945. Minute obligate intra- cellular parasites of varied form, commonly Gram negative but with Gram positive granules. There have been many observations of bodies of the characters stated, but a satis- them is not yet possible. Howard Taylor Ricketts showed factory classification of that Rocky Mountain spotted fever is transmitted by the tick Dcrmocentor, and observed, in the cells of diseased tissues, minute irregularly staining bodies; in 1910,  Kingdo7n Mychota [21 in the course of further studies of the disease, he contracted it and died. Stanislas Prowazek, called into the Austrian military medical service in 1914, began to study typhus, which is transmitted by lice; observed similar intracellular bodies; contracted typhus, and died in February, 1915 (Hartmann, 1915). The cause of Rocky Mountain spotted fever is Rickettsia Rickettsii, and that of typhus. is R. Prowazekii. Several other species are known. By serological methods, Anigstein (1927) showed that R. Melophagi is closely related to Corynebacterium. In cases of the disease of the west slope of the Andes called verruga peruana, Oroya Fever, or Carrion's disease, there occur intracellular bodies named Bartonella bacillijormis. Noguchi and others (192H) completed the demonstration that the disease is transmitted by biting flies of the genus Phlebotoyniis. Good authority has construed Bartonella as a sporozoan. Students of flagellates, Sarkodina, and Infusoria have occasionally observed in the cytoplasm or nuclei of these organisms minute bodies multiplying to form consid- erable masses. These parasites have generally been construed as chytrids, but have little in common with proper chytrids. The genus Caryococcus Dangeard includes at least a part of them. Family 5. Kurthiacea, fam. nov. Gram positive peritrichous rods, not producing endospores. Kurthia, harmless; Listeria Pirie ex Murray in Bergey's Manual 6th ed. 408 (1948), pathogenic in sheep and man. Family 6. BaciUacea [Bacillacei] Fischer in Jahrb. wiss. Bot. 27: 139 (1895). The spore-forming rods, always Gram positive, mostly peritrichous, very numerous in species, common, and important. Bacillus Cohn 1872, is one of the oldest generic names of rod-shaped bacteria which can be can be definitely applied because the type species definitely applied: it The genus has been used to include B. subtilis was so described as to be recognizable. rods in general or at random. Defined as aerobic spore-formers, as proposed by Buchanan, 1917, it is a thoroughly natural group. As treated in the fifth edition of Bergey's Manual, it included nearly 150 duly distinguished species; in the sixth edition, this number is cut to thirty-three. The great majority are saprophytic. Ex- ceptions, important pathogens, are B. anthracis; and B. alvei and other species causing foulbrood of bees. The anaerobic spore-formers constitute the genus Clostridium. The type species wa? discovered and named three times in different connections. As an anaerobe involved in the fermentations which give butter its flavor, it is C. butyricum Prazmow- ski.As an organisms whose cells contain granules staining like starch, it is Bacillus Amylobacter van Tieghem. It has the property of fixing nitrogen; discovered in this capacity by Winogradsky (1902) it was named C. Pastorianum. The species of Clostridium, as of Bacillus, are numerous. They are primarily saprophytic, but many species produce powerful toxins and are serious pathogens. Examples are C. tetani; C. botulinum; and C. septicum and a whole roll of other species, causing various forms of gangrene, occasion for the study and distinction of which was found during World War I. Family Achromobacteriacea [Achromobacteriaceae] Breed 1945. Family Bac- 7. teriaceae McNabin Jour, of Bot. 15: 340 (1877), based on a generic name which must be abandoned as a nomen conjusum. Family Enterobacteriaceae Rahn 1937, not based on a generic name. Gram negative rods which lack the dictinctive characters of the families subsequently to be treated. 22 ] The Classification of Lower Organisms The nine genera listed first occur normally in animals, mostly in the gut and mostly as commensals; exceptions are important pathogens. Most of them produce acid, and many of them produce gas, from sugar. These genera are the traditional colon-typhoid-dysentery group. Escherichia coli, the colon bacillus, and Aerohacter aerogenes, the gas bacillus, are common commensals which produce acid and gas from dextrose and lactose. The standard method of testing waters for contamination is essentially a test for the presence of these organisms. Klebsiella also produces acid and gas from sugars. It inhabits the respiratory tract. The cells are heavily capsulated and non-motile. The type species K. pneumo- niae an important pathogen, the pneumobacillus of Friedlander. is Proteus vulgaris (this is at least the third genus to bear the name Proteus, but the first in this kingdom) produces acid and gas from dextrose but not lactose, and liquefies gelatine. It is usually isolated from spoiled meat. Salmonella is distinguished from Proteus by non-liquefaction of gelatine. Many of its species are harmless commensals; others cause paratyphoid fevers. Immunologi- cal study of cultures of Salmonella from cases of disease and from waters have re- sulted in the distinction of fully 150 races, mostly unnamed and identifiable only by immunological reactions. Eberthella includes motile rods producing acid but not gas from sugars, and belonging to the same immunological system as the various races of Salmonella. Eberthella typhi causes typhoid fever. Shigella is distinguished from Eberthella by non-motility. The Shiga bacillus, S. dystenteriae, is the cause of dystentery. Bacteroides numerous group of acid-producing gut bacteria, motile or non- is a motile, generally harmless.^ distinguished from the foregoing as strictly anaerobic. Alcaligenes fecalis, an apparently harmless organism isolated from intestinal con- tents, does not produce acid from sugars; grown in milk, it produces an alkaline reaction. Numerous races of bacteria which have been and are capable isolated from soil which produce of attacking cellulose are assigned to the genus Cellulomonas. Bacteria an extracellular red pigment are Serratia (one of the oldest generic names for bac- teria); those which produce yellow pigment are Flavobacterium; those which produce blue, black, or violet growths are Chromobacterium. Cultures which lack the distinc- tive characters of all of the above named genera (most such cultures have been isolated from water) are called Achromohacter. Family 8. Pasteurellacea nom. nov. Family Parvobacteriaceae Rahn; there is no corresponding generic name. Minute non-motile Gram negative rods, pathogenic, requiring special media for cultivation. Pasteurclla avicida is the cause of chicken cholera, upon which Pasteur made important studies. Of greater direct importance to man is Pasteurella pestis, the cause of plague. Hemophilus includes the agents of whooping cough, soft chancre, and conjunctivitis. Brucella includes the organisms which cause Malta fever, undulant fever. Bang's disease, contagious abortion. Pfeif- ferella mallei is the cause of glanders. Family 9. in Jour. Bact. 36: 321 (1938). Gram Rhizobiacea [Rhizobiaceae] Conn negative rods, atrichous or peritrichous, parasites on plants. Cultured in the presence of sugars, these organisms produce acid; they are evident allies of the colon group. Erwinia commemorates Erwin F. Smith, the discoverer of many bacteria pathogenic to plants. Typical species cause blights, wilts, or dry necroses. The discovery by Burrill, 1882, of Erwinia amylovora, the cause of the fire blight of pears, should  Kingdom Mychota [ 23 have prevented the formulation of a theory, once entertained, that all bacteria require neutral media, and are accordingly incapable of causing diseases of plants. The species of Pectobacterium, as P. carotovorum, cause rots. Those of Agro- bacterium cause galls; A. tumefaciens causes crown gall of many plants. Rhizobium includes the species which produce little galls ("nodules") on the roots of plants and which benefit their hosts by fixing nitrogen. The best known hosts of Rhizobium are plants of the family Leguminosae; the relationship between Leguminosae and Rhizobium is a classic example of symbiosis. There are several or many species of Rhizobium, scarcely distinguishable morphologically, but living on different groups of legumes. The race which was first recognized and isolated, R. Leguminosarum Frank 1890 [Schinzia Leguminosarum Frank 1879; Bacillus Radicic- ola Beijerinck 1888) is that which attacks plants of the pea tribe. Bewley and Hutch- inson (1920) accounted for the variety of forms which Rhizobium can assume. In the roots of plants it occurs as involution forms. In culture, it is a peritrichous rod, but the flagella are often reduced to one, and it has been confused with the mono- trichous bacteria (Conn and Wolfe, 1938). Family 10. Azotobacteriacea [Azotobacteriaceae] Bergey, Breed, and Murray in Bergey's Manual 5th ed., preprint, v and 71 (1938). These are the organisms which were originally isolated by Beijerinck (1901) by inoculating with garden soil shallow layers of a nitrogen-free nutrient solution containing mannite. The commonest species, Azotobacter Chroococcum, is usually seen as ellipsoid cells, as much as \\x thick and 7[J. long, solitary, with peritrichous flagella, or forming non-motile clusters imbedded in a heavy capsule. Beijerinck observed the occurrence of globular involution forms as much as 15^ in diameter. Lohnis and Smith (1916) made a thorough study of variations in form, and reported a remarkable variety of other stages, including the symplasm. The Pasteurellacea and Rhizobiacea are apparently reasonably close allies of the Achromobacteriacea. The Azotobacteriacea stand somewhat apart. The remain- ing families of the present order are more definitely distinct, being marked by mono- trichous or lophotrichous flagella. Family 11. Migula 1894. Family Pseudomonadaceae Spirillacea [Spirillaceae] Winslow 555 (1917). Rods and spirals, Gram negative, mono- et al. in Jour. Bact. 2: trichous or lophotrichous; not producing much acetic acid, and mostly heterotrophic. Pseudomonas is a numerous genus of rods which may or may not produce a fluores- cent pigment soluble in water; they do not produce a yellow pigment which is in- soluble in water. The original species, P. aeruginosa, was isolated from pus, in which it produces a blue-green discoloration; it is by itself weakly if at all pathogenic. Other species have been isolated from fresh and salt waters and brines; the bacteria which produce phosphorescence on salt fish are of this genus. Many further species arc: pathogenic to plants, producing chiefly leaf spots. Phytomonas Bergey et al. 1923 {Xanthomonas Dowson 1948) includes numerous plant pathogens which in culture produce an insoluble yellow pigment; among them are the causes of cabbage rot, walnut blight, and leaf spots on many plants. Pacinia Trevisan 1885 includes monotrichous curved rods. The type species P. cholerae-asiaticae is the cause of Asiatic cholera. Among numerous other species the majority are harmless saprophytes in waters. Recent authorities have treated the cholera organism as the type of the genus Vibrio Miiller (1773); their action is an in- tolerable falsification of the usage of a full century preceding the discovery of the cholera organism. 24 ] The Classification of Lower Organisms Spirillum includes the typical spirals, lophotrichous, a small number of species of harmless saprophytes in foul waters. Thiospira includes large lophotrichous spirals, colorless, containing granules of sulfur. They are believed to live by chemosynthesis. Family 12. Acetobacteriacea [Acetobacteriaceae] Bergey, Breed, and Murray 1938. As gross objects, growths of Acetobacter aceti Beijerinck have been known since prehistoric times. With included yeasts they constitute mother of vinegar (the old names Mycoderma mesentericum Persoon, Ulvina aceti Kiitzing, and Umbina aceti Nageli designated the combination of bacteria and yeasts, and it seems proper to reject them). Free-swimming cells with polar flagella have been observed; ordinarily the cells appear as rods in chains, heavily encapsulated, or as involution forms. The organic food required by Acetobacter is alternatively alcohol, which is oxidized to acetic acid, or acetic acid, which is oxidized to carbon dioxide and water. These processes are strictly aerobic: to make vinegar, one exposes wine to air; to preserve it, one seals the vessels. Family 13. Nitrobacteriacea [Nitrobacteriaceae] Buchanan in Jour. Bact. 2: 349 (1917). Organisms oxidizing the simplest organic compounds; or facultatively capa- ble of chemosynthesis; or living strictly by chemosynthesis and strictly aerobic: mostly Gram negative monotrichous or atrichous rods. Methanomonasis capable of oxidizing methane; Carboxidomonas of oxidizing carbon monoxide; Hydrogenomonas, of oxidizing elemental hydrogen. Thiobacillus includes organisms which oxidize hydrogen sulfide or elemental sulfur. Winogradsky had discovered chemosynthesis in the course of studies of Beggiatoa and other sulfur-oxidizing organisms before he undertook to isolate bacteria which cause nitrification, that is, the natural production of nitrates in soil and waters. He achieved success (1890) by inoculating, with soil or sewage, media which con- tained salts of ammonia but no food; he saw the nitrifying organisms first as minute motile rods which he named Nitromonas. Further study and the use of solid media showed that nitrification takes place in two stages and is the work of several kinds of organisms. Winogradsky distinguished Nitrosomonas europaea and N. javaneyisis, monotrichous rods from different regions as indicated, oxidizing ammonia to nitrites; Nitrosococcus, non-motile spheres from South Amerca, effecting the same oxidation as Nitrosomonas; and Nitrobacter, non-motile rods oxidizing nitrites to nitrates. Subsequent authors have validated Winogradsky's names by creating the combina- tions Nitrosococcus nitrosus and Nitrobacter VVinogradskyi. Subsequently, Winograd- sky discovered yet other bacteria capable of the same oxidations. The presence of nitrifying bacteria is necessary for the normal growth of most crops. So active are the nitrifying bacteria that no more than traces of ammonia and nitrites are found in normal soils, and so avidly do plants absorb nitrates that these accumulate only in fallow fields. Order 2. Actinomycetalea [Actinomycetales] Buchanan in Jour. Bact. 2: 162 (1917). Organisms which consist typically of slender filaments not divided into cells, but which are capable of producing conidia, that is, minute spherical or elongate bodies cut off by constriction from the ends of the filaments, or of breaking up into cells of the form of regular or irregular rods. Non-motile; Gram positive or Gram negative; often of the staining character called acid fast. The order may be treated as a single family.  Kingdom Mychota [ 25 Family Mycobacteriacea [Mycobacteriaceae] Chester 1907. Family Actinomyce- taceae Buchanan in Jour. Bact. 3: 403 (1918). Family Streptomycetaceae Waksman and Henrici 1943. Characters of the order. Three genera require discussion. Streptomyces Waksman and Henrici 1943. The original name of this genus is Streptothrix Cohn (1875); there is an older genus Streptothrix among plants, and the numerous species of the present genus have generally been included in Actino- myces. Cultures are readily isolated from air or soil. They appear as slowly growing colonies which may at first be of various colors and have shiny surfaces. Their texture is tough; a blunt needle will more often tear a colony from the medium than pene- trate it. As the colonies grow, they become truncate; the exposed surfaces become white and powdery; pigments, black, brown, red, or yellow, in various races, are produced, and discolor the medium. The toughness of the colonies is a consequence of their structure, of myriad crooked branching filaments about 1|J. in diameter, without joints; the white and powdery surface is produced by myriad conidia released in basipetal succession. The cultures are of an odor which may be described as that of earth under the first rain after drouth: undoubtedly, this familiar odor is that of Streptomyces in the soil. Drechsler (1919), from careful study of several species of Streptomyces, concluded that they are fungi; their filaments are, however, much finer than those of fungi, and no definite nuclei have been seen. Certain species of Streptomyces cause a scabbiness of potatoes. Except for this, the genus was for a long time regarded as quite unimportant. When the capacity of the fungus Penicillium notatum to inhibit the growth of bacteria had been observed, and had led to the discovery of the drug penicillin, Waksman, the leading authority on the classification of Actinomycetalea, sought comparable drugs produced by Streptomyces, and had the great success of discovering streptomycin. Actinomyces Bovis Harz 1877 is one of several species of the same general nature as Streptothrix which are pathogenic to animals. It causes lumpy jaw of cattle. Mycobacterium Lehmann and Neumann 1896 is typified by M. tuberculosis, the agent of one of the most important diseases of man, supposed originally to have attacked cattle, and to have spread around the world with European cattle. It is a chronic disease, destroying the tissues slowly and producing a nugatory sort of im- munity which makes it possible to test for the disease, but does not check it. The cells are recognized in sputum and in diseased tissues by the acid fast reaction: the dye carbol fuchsin must be applied hot in order to color them; once it has done so, it does not wash out in acid alcohol. It is cultivated with difficulty. The growth is dry, powdery, wrinkled, with an odor desc