AMOEBAE OF THE INTESTINAL TRACT. 219 



conclusions regarding certain points connected with 

 the developmental history, such as the conditions hast- 

 ening or retarding the various stages of growth, or 

 the intervals of time which elapse between the amoebic 

 and the flagellate stage, and the time consumed in 

 the development of swarm-spores, I have been able 

 to study each stage of development and to confirm 

 in this species the description given by Schaudinn of 

 the life-cycle of Paramceba eilhardi. 



Beginning with the amoebic stage, the parasite 

 reproduces by simple division for a certain period, 

 probably for as long as conditions are favorable to 

 its vegetative existence, and during this time its struc- 

 ture is that of a typical amoeba. Encystment is in- 

 itiated by the organism becoming motionless, assum- 

 ing a spherical shape, and then rotating rapidly, the 

 cyst wall being formed during the process of rota- 

 tion. When encystment is complete, the organism 

 again becomes motionless, and a refractive, double- 

 outlined cyst wall is then distinguishable. Within 

 the cyst there soon appear numerous small, round, 

 refractive bodies, which finally escape from the cyst, 

 each body possessing a single, long flagellum, of very 

 delicate structure. These little flagellates are 

 actively motile, increase considerably in size, and 

 undergo longitudinal division for several generations. 

 At the end of this period of reproduction the para- 



