, DEVELOPMENT OF SPERMATOBIUM. 9 



In the first stages when the first cytospheres are formed 

 their bodies are somewhat smaller, but they quickly in- 

 crease in size; at least, the more numerous the larger 

 they are up to a certain point. The first cytospheres are 

 seen only near the surface, below the cytotheca, irregu- 

 larly distributed in groups, like land and oceans on a map. 

 What I consider the adult individual is solid, so to say,' 

 with cytospheres, the vacuoles then having entirely dis- 

 appeared, and even the interior containing cytospheres. 



CYTOSPHERES. 



The cytospheres are small, perfectly globular, glassy, 

 pellucid bodies, which do not stain with orange G., and 

 only very faintly with h^motoxylon, though the latter can 

 hardly be called staining, but may rather be termed soil- 

 ing. In fact, they remain pellucid to the last, with the 

 exception of a central spot of darker color, the latter, 

 however, not being due to any stain. Soon after the ap- 

 pearance of the cytospheres this spot is seen to be very 

 small, exceedingly well defined and very dark, merely 

 appearing as a single point (figs, lob, 14), sometimes 

 surrounded by a white zone. 



At what I suppose a later stage in the cytosphere, this 

 central dot or cytosphero-center enlarges and appears as 

 a small circular disc (fig- 16), also well defined, the 

 boundary being much the darkest. At a later stage yet, 

 the cytosphero-center becomes diffuse, and gradually oc- 

 cupies a large part of the cytosphere. This is the charac- 

 ter of the cytospheres at the end of the formation of the 

 sporogonia and sporoblasts(figs. 18, 20) . After the pseudo 

 navicella spore is formed, the cytospheres diminish in 

 size, and finally are seen to possess only about one -half 

 the diameter of the original cytosphere (fig. 26). I be- 

 lieve this diminished size is caused by a division of the 

 cytosphere into four parts, as I have observed a number 



