ANIMAL PARASITES. 129 



quently, especially when the amoeba is active, a portion of the proto- 

 plasm appeal's almost homogeneous ectosarc while the rest endosarc 

 is granular. When moving it assumes various forms, thrusting out 

 and withdrawing nearly homogeneous pseudopodia. It may also change 



FIG. 52. AMCEBA COLI. 

 From the intestinal wall near an ulcer in amoebic colitis. 



its shape without progressive movement. It occurs in acute and chronic 

 dysentery, frequently in Egypt, occasionally in Russia, and is often seen 

 in the United States. ' 



Other species of amoeba have been found parasitic in the human 

 mouth, intestines, and bladder. 



II. MASTIGOPHORA. 



These organisms, many forms of which are closely related to the Sar- 

 codina, are of definite or changeable shape, with or without a membrane ; 

 some are parasitic, some saprophytic. They are characterized by the 

 possession of one or more motile flagella. They are frequently grouped 

 in colonies. 



Among the flagellated protozoa, the group of Trypanosomes are of 

 much significance, as parasites in frogs and other cold-blooded as well as 

 in warm-blooded animals. These organisms are fusiform in outline, 

 with a single flagellum and an undulatory membrane. They have been 

 long known in the blood of rats and are of frequent occurrence in cattle, 

 horses, dogs, and other related animals. Among the recognized diseases 

 of animals believed to be due to trypanosomes are: Xagaua the tsetse- 

 fly disease ; Surra ; and several other maladies of wild and domestic 

 animals of subtropical and tropical regions. Trypanosomata appear to 

 be common in wild rats in all countries. A few cases of trypanosomatic 

 infection in man in Africa are recorded. Xovy and McXeal have re- 



1 We refer for further details concerning the Amoeba coli to the work of Council- 

 man and Lqflevr on "Amoebic Dysentery." Johns Hopkins Hospital Reports, vol. ii., p. 

 395, 1891. For a method of differential staining of the Amoeba coli see Mallory, Jour- 

 nal of Experimental Medicine, vol. ii., p. 529, 1897. 

 9 



