Kingdom Mychota [ 29 



Spirochaeta plicatilis and other saprophytic species, together with certain species 

 parasitic in mollusks, are fairly large. The species which are parasitic or commensal 

 in other animals may be extremely small. It is chiefly by study of the larger species 

 that the structure is known. The internal structure is septate. Dobell (1911) found 

 in Cristispira, at the margin of each septum, a whorl of granules staining like chroma- 

 tin, and interpreted these granules collectively as a nucleus. Noguchi (in Jordan and 

 Falk, 1928) saw in the interior of the smaller species no chambered structure, but a 

 lengthwise rod. This has been interpreted as a nucleus, as a locomotor or skeletal 

 structure, or as an artifact. The electron microscope has shown actual flagella at the 

 ends of cells of Treponema pallidum. Reproduction is normally by transverse divi- 

 sion into two. During division, the daughter cells may coil about one another, giving 

 a false appearance of lengthwise division. Gross (1913) observed that Cristispira is 

 capable of breaking up into cylindrical Stdhchen corresponding to the chambers. 



The discovery of Treponema by an eminent protozoologist; the character of 

 spirochaetal diseases, several of which are spread by biting insects, and produce only 

 that nugatory immunity which makes diagnosis possible but does not check the 

 disease; and the supposed lengthwise division of the cells; led to the hypothesis that 

 the spirochaets are protozoa. Dobell was surely correct in dismissing this hypothesis, 

 insisting that the spirochaets are neither protozoa nor typical bacteria, but a group 

 sui generis. 



The larger and smaller spirochaets are reasonably treated as separate families. 



Family 1. Spirochaetacea [Spirochaetaceae] Swellengrebel 1907. The cells com- 

 paratively large, 80-500(1 long. Spirochaeta, Saprospira, Cristispira. 



Family 2. Treponematacea [Treponemataceae] Robinson in Bergey Man. 6th ed. 

 (1948). Family Treponemidae Schaudinn 1905. The cells 4-15^ long. 



Treponema Schaudinn. The cells comparatively loosely coiled. T. pallidum, the 

 agent of syphillis. T. pertenue, the agent of yaws. T. macrodentium and T. micro- 

 dentium, harmless commensals in the mouth. 



Borrelia Swellengrebel is doubtfully distinct from the foregoing; Noguchi reduced 

 it. B. recurrentis and other species cause relapsing fevers. B. Vincenti causes Vincent's 

 angina (trench mouth). The fusiform cells always found associated with it and 

 supposed to be ordinary bacteria of a genus Fusiformis or Fusobacterium may be its 

 chlamydospores. 



Leptospira Noguchi. The cells tightly coiled. L. icterohaemorrhagiae is the agent 

 of infectious jaundice. L. icteroides, isolated by Noguchi in South America, sup- 

 posedly from cases of yellow fever, is perhaps the same thing: it is now known that 

 yellow fever is caused by a virus. It was in pursuing in Africa his study of yellow 

 fever that Noguchi lost his life by this disease (Flexner, 1929; Eckstein, 1931). 



Class 3. ARCHSPLASTIDEA Bessey 



Myxophykea Wallroth 1853. 



Myxophyceae Stizenberger 1860. 



Division (of Class Algen) Pkycochromaceae and order Gloiophyceae Rabenhorst 



Krytog.-Fl. Sachsen 1: 56' (1863). 

 Cyanophyceae Sachs Lehrb. Bot. ed. 4: 248 (1874). 



OrAtx Cyanophyceae or Pkycochromaceae yicNdLhm]o\iT. oi'Qot. 15: 340 (1877). 

 Schizophyceae Cohn 1879, not suborder Schizophyceae Rabenhorst Deutschland's 



Kryptog.-Fl. 2, Abt. 2: 16 (1847). 



