PROTOZOA 



505 



PROTOZOA 



We designate as protozoa the primordial animals, those microscopically 

 small but living organisms which, as monocellular elements, singly or in colo- 

 nies, collectively represent the simplest animal type. The substance of the 

 body, sarcode, consists of a contractile, finely granulated protoplasm which is 

 mononuclear or polynuclear. The viscid, hyaline ectosarc is capable of motion 

 by contraction and expansion, or by extension and retraction of pseudopodia, 

 by cilia and flagella. There can be no doubt that it is concerned in the inges- 

 tion and excretion of food. Fissures and openings in the ectosarc take the 

 place in some protozoa of the functions of mouth and anus. The soft endo- 

 sarc serves for the digestion of the food consumed; the contractile vacuoles, 

 occurring in many protozoa, are intended for the accumulation of fluids to be 

 excreted. Propagation takes place by segmentation, gemmation or sporulation. 



We know that all three varieties of the protozoa, the rhizopoda, the sporozoa 

 and the infusoria, occur as parasites in man. 



The rhizopoda, " root-footed " organisms, include the amceba coli (Loesch), 

 discovered in 1875, the amosba coli felis of Quincke in 1893, the amoeba coli 

 mitis of Quincke, which is minutely described in the interesting treatise of 

 Hoppe-Seyler, " Dysentery and Ameba Enteritis," ^ and the amoeba coli vul- 

 garis of Quincke. The investigations of Quincke and Eoos have proven that 

 the latter are not pathogenic either in man or in cats. The severe and well- 

 knovm dysenteric symptoms caused by the first-named ameba may be mate- 

 rially complicated by the supervention of liver abscesses. Cases of infection 

 by amoeba coli mitis are considerably milder, but of a distinctly chronic course. 

 For details regarding these parasites I refer to the previously mentioned article. 



Amebaa in man are not confined to the intestines. I have referred to their 

 occurrence in the pus of liver abscesses in dysentery. Jjima demonstrated 





/ 



Fig. 28. — Ameba Flat- 

 tened. 



FiQ. 26. — Ameba at Fig. 27. — Ameba in 



Rest. Motion. 



Figs. 26-28. — Leydenia Gemmipaea. (After von Leyden-Schaudinn.) 

 n, nucleus; v, vacuole; ■pv, pulsating vacuole. 



amebee in pleuritic and peritoneal exudates. Gros and Sternberg have reported 

 the presence of amebas in the tartar of the teeth. Flexner found amebse in an 

 abscess in the oral cavity, Kartulis in the pus and in an extracted portion of 



1 See the chapter on Dysentery in volume, " Infectious Diseases.' 



