6 CALIFORNIA ACADEMY OF SCIENCES. 



into the sperm-sac. This stage is intracellular, the par- 

 asites having entered the cell and are feeding on its con- 

 tents. In size the young Spermatobium is there not any 

 larger than the fully developed spore (fig. la, b, c), though 

 I do not thereby wish to^say that it is the spore which has 

 been transformed into an immature Spermatobium, as on 

 this point I am yet in doubt. This stage is but slightly 

 larger than the nucleus of the spermatogonium of the 

 host (fig. la). 



The protozoan may at this stage be described as a small 

 cell with nucleus and nucleolus, the cell being of various 

 forms, round or oblong, the nucleus always round and the 

 nucleolus globular and well defined. Generally, how- 

 ever, the protozoan is pointed oviform, as in the fig. la. 

 In the following I will always refer to the two or three 

 principal parts of the protozoan as cell or cytosome, nu- 

 cleus or caryosome and nucleolus, the definitions of which 

 are the general accepted ones. The cytotheca is thin 

 and structureless, frequently wavy and ruffled. 



THE CYTOPLASM. 



The cytoplasm consists of at least two distinct parts^ 

 which, however, are not always localized, and which 

 can in no way be designated as ectoplasm and entop- 

 lasm. At times the cytoplasm appears uniform, slightly 

 grainy; at other times, or generally, there is a coarser 

 granulation in the pointed end of the cytosome, as in fig. 

 la. In this figure the nucleus of the spermatogonium 

 is seen to the right in the upper corner. In the lower 

 corner of the protozoan the cytoplasm is seen to be coarser,, 

 though it is not always darker. The fact that at this stage 

 the protozoan is intracellular makes observation difficult 

 and less exact. I think, however, that these two differ- 

 entiations of the cytoplasm correspond to those found in 

 the free and adult form, and soon to be described. 



