22 CALIFORNIA ACADEMY OF SCIENCES. 



gular outlines, probably the indication of amoeboid move- 

 ments (fig. 35). In this free stage the shuttle spores 

 nearly always contain a distinct nucleus situated generally 

 at one of the poles, but sometimes also in the middle of 

 the convex side. 



While I have found these shuttle spores in great num- 

 bers, I have observed only very few real pseudonavicellse 

 forms. These pseudonavicellse spores are of the same 

 size as the former, but differ considerably in their struc- 

 ture. 



Their cytotheca is very thick, projecting into a knob 

 at each pole (fig. 27). The cytotheca contains a single 

 row of very minute, dark, entirely opaque globular bodies, 

 which in the knob-like projections at the poles are more 

 thickly accumulated. 



Their contents consist of cytospheres of much smaller 

 size probably due to a further division of those found in 

 the shuttle form of spore, in the manner as indicated in 

 fig. 33(?'. A large nucleus appears present in at least 

 some of the spores, but the scarcity of these spores has 

 prevented me from studying its development and form. 

 So far I have never observed the sickle germs found in 

 Monocystis, as well as in a large number of other sporozoa. 



In this description I have assumed that what I have 

 here called pseudonavicellse spore is a direct modification 

 of the shuttle spore. I must, however, add that I have 

 never found one of these pseudonavicell^ in the sporo- 

 gonium, but always scattered loose among the shuttle 

 spores. 



DIVISION OF THE ADULT. 



A division of the adult form, as well as of the sporo- 

 gonium, is frequently observed. In figures 38 to 42 I 

 have endeavored to figure a series of such divisions. 

 Fig. 38 represents an adult with large cytospheres, and 



