THE ENCYSTMENT OF MAOBOBIOTUS. 11 



Ges. 1906, p. 267). Prof. Lauterborn's observations differ from 

 mine in many respects, and it may be that the cycle of changes 

 is not identical in the two species. It is curious that these two 

 species, which are believed by Prof. Piichters to very closely 

 resemble each other, yet differ profoundly in the details of repro- 

 duction, as shown by the recent discovery of the spiny eggs of 

 M. dispar. Prof. Lauterborn also refers to this remarkable pro- 

 cess as encystment (Encystierung). Both M. macronyx and M. 

 dispar live in ponds, and we might find in this the cause com- 

 pelling to the encystment, but M. echinogenitus, which also 

 encysts, is not especially a pond-dweller. 



