. Parasites and parasitosis of the domestic animals : the zoo?logy and control of the animal parasites and the pathogenesis and treatment of parasitic diseases . Domestic animals. 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 m
. Parasites and parasitosis of the domestic animals : the zoo?logy and control of the animal parasites and the pathogenesis and treatment of parasitic diseases . Domestic animals. 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 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. mar
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