THE PROTOZOAN SUBGROUPS 



327 



asitic forms, and most of those which are free-living, obtain their nour- 

 ishment by absorbtion through the general surface of the bodj'. 



The parasitic flagellates come within two orders, — Spirochetida and 

 Trypanosomatida. 



Order I. Spirochetida 



Flagellata (p. 326). 



The spirochetes are of somewhat uncertain position because of in- 

 complete knowledge of their flagella and life history. They multiply by 

 longitudinal division, or it may be by transverse division as do bacteria, 

 and many writers have placed 

 them with the latter organisms. 

 They range from one to two 

 hundred microns in length, and 

 the body is filamentous and 

 spiral in form (Fig. 169) . Deli- 

 cate flagella maj^ be present at 

 one or both ends. Nuclei can- 

 not be distinctly demonstrated; 

 the nuclear material is prob- 

 ably distributed as granules 

 throughout the protoplasm as 

 in bacteria. Motility is exhib- 

 ited by rotatory movements, 

 and the progression may be in 

 either direction. 



Excepting in poultry, the spirochetes are not, so far as known, seriously 

 pathogenic in the domestic animals. The extreme pathogenicity of 

 certain spirochetes in man, however, indicates the disease-producing 

 possibiKties of the group and rates it, potentially at least, as a dangerous 

 one to all higher animals. 



Fig. 169. — Spirocheta pallida (after Craw- 

 ley, from Dofiein, after Schaudinn, Cir. No. 194; 

 Bu. An. Ind., U. S. Dept. Agr.). 



Spirochetosis of Fowls 



This disease was first described by Marchoux and Salimbeni who, 

 working in Brazil, noted that special varieties were more susceptible 

 and suffered more severely from the attack than common fowls. The 

 condition was originally termed fowl septicemia, or Brazilian septicemia 

 of fowls, and is now considered to be due to the presence of the spirochete 

 Spirocheta gallinarum (S. marchouxi) which lives in the blood, is 15-20 

 microns in length, and is carried from host to host by the tick Argas 

 miniatus. 



The investigators above mentioned distinguish an acute and chronic 

 form of the disease, the former characterized by emaciation, drooping, 



