92 PARASITIC AMOEBAE OF MAN. 



The entire cytoplasm in the vast majority of Ent- 

 amceba coli appears to be composed of endoplasm, as 

 the differentiation of the ectoplasm is impossible in 

 most instances. In the very young amoebae of this 

 species the cytoplasm is homogeneous throughout. 



During motion the pseudopodia, which are 

 formed by the ectoplasm, appear to be somewhat less 

 refractive than the endoplasm, and of very slight 

 consistence. Sometimes the pseudopodia are only 

 visible upon careful focussing, resembling a veil-like 

 membrane projecting from some portion of the pe- 

 riphery of the parasite. 



Vacuoles and Contained Bodies. The vast ma- 

 jority of parasites belonging to this species present 

 a finely granular cytoplasm in which no vacuoles can 

 be observed. In the thousands of specimens studied 

 by myself a vacuole was present in but a little over 

 10 per cent, of the parasites and a very small per- 

 centage showed more than one vacuole. When pres- 

 ent the vacuole is of small size, and never contractile. 

 The absence of vacuoles in this species is in striking 

 contrast to the numerous vacuoles observed in Enta- 

 mceba histolytica, and other pathogenic amoebae, and 

 is of some value in the differentiation of this species. 



The endoplasm contains refractive dots and rods, 

 some of which are micrococci, bacilli, and various 

 crystals derived from the feces, while the nature of 



