I30 CLASSIFICATION OF BACTERIA 



by some of the filamentous forms. Chlorophyll is produced by none of the bacteria (with the 

 possible exception of a single genus). Many forms produce pigments of other types. The 

 cells may be motile by means of fiagella; some of the forms intergrading with the protozoa 

 are flexous, a few filamentous forms (as Beggiatoa) show an oscillating movement similar to 

 that of certain of the blue-green algae (as Oscillatoria) . 



The Committee used the following description: 



Minute, one-celled, chlorophyll-free, colorless, rarely violet-red or green-colored plants, 

 which typically multiply by dividing in one, two or three directions of space, the cells thus 

 formed sometimes remaining united into filamentous, flat, or cubical aggregates. Capsule 

 or sheath composed in the main of protein matter. The cell plasma generally homogeneous 

 without a nucleus. Sexual reproduction absent. In many species resting bodies are pro- 

 duced, either endospores or gonidia. Cells may be motile by means of flagella. 



Under the Schizomycetes a number of orders have been proposed, in some of which 

 there is general agreement and in some less. In the discussion following, except where 

 a definite published group is referred to, I shall attempt to avoid the technical terms, 

 using groups, forms, kinds, etc., as well as the common term "bacteria" or "cocci" to 

 indicate rods or spheres. 



Among the groups generally known as "higher bacteria" and less important to 

 the medical bacteriologist there is a great deal of agreement. 



Under the Schizomycetes the groups of the sulphur {thio-) bacteria, the sheathed 

 (chlamydo-) bacteria, and the pseudoplasmodial (myxo-) bacteria are fairly well ac- 

 knowledged and contain much the same material the world over, though the rank is 

 not always the same. This leaves us the "true bacteria" {Eubacterlales [Buchanan]) 

 with the border-line groups of "actino-" and spiral forms. 



Taking up first the border-line groups of thread forms and spiral forms, the sum- 

 mary of their history leading to the present status is about as follows: 



Actinomyces — In 1877 Harz described the thread fungi in "lumpy jaw" of cattle 

 as "actinomyces" and started the group on its quarrelsome path. Rivolta in i8/3 

 preferred "discomyces," and various observers (Blanchard [1895], Brumpt [1910], and 

 Merrill and Wade [1919]) agree with him. Streptothrix (Cohn) is accepted by others, 

 but there is apparently reason to believe this term invalid (Buchanan, p. 497), though 

 it still has plenty of adherents. Study of the group brought out the fact that there are 

 two distinct methods of reproduction within the group, and Trevisan in 1899 sug- 

 gested the name Nocardia for those forming spores, as distinguished from the non- 

 spore-forming ''actinomyces,'" a term accepted by Wright in 1904. Buchanan (p. 405) 

 regards it as a synonym. Thus we have four names, each more or less ably supported 

 as the ten pages devoted to the subject by Buchanan indicate. The Committee adopts 

 Actinomycetales as an order, as do also Buchanan and Bergey, while Breed, Conn, and 

 Baker consider them as a family — Actinomycelaceae. 



Whatever name we prefer and select, new arguments arise as to the contents of 

 the group (see Table I). Some authors under the prefix "actino-" include the thread 

 fungi and also the tubercle-bacillus group and the diphtheria group, others include the 

 same series under the prefix "myco-," while others separate the thread fungi from the 

 "myco-bacteria," placing these last directly among the non-spore-forming rods. The 

 modern tendency, since Lehmann and Neumann, seems to be to place tuberculosis 



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