20 CALIFORNIA ACADEMY OF SCIENCES. 



distribution as regards each other (figs. lo to 13), the 

 cytospheres appear to group themseh^es in certain num 

 bers around each nucleus. The number of such cyto- 

 spheres varies, the new sporoblasts being similarly of va- 

 rious sizes, not, however, differing greatly, some beings 

 nearly twice as large as others. It would appear as if 

 the micronuclei possessed two distinct properties, one 

 of which is to repel each other, which would cause 

 them to be regularly distributed; and one to attract the 

 cytospheres, which would explain the comparatively even 

 distribution of the latter and their collecting to form spo- 

 roblasts. The sporoblasts become surrounded with a 

 thin membrane, which becomes thicker just before the 

 forming of the lunate and shuttle spore. As to the proc- 

 ess of forming these spores I am unable to give any sat- 

 isfactory account. It appears to me, however, as if in 

 the final, smallest and ultimate sporoblast, we find several 

 micronuclei scattered about among the cytospheres which 

 at this stage begin to further divide. After the sporoblasts 

 have begun to form — that is, after the cytospheres have 

 begun to arrange themselves into agglomerate balls (spor- 

 oblasts) — the whole individual, now a sporogonium, in- 

 creases in size, and finally divides itself into two or more 

 smaller or microsporogonia. The ultimate size of these 

 sporogonia varies. It is probable that all the micro- 

 sporogonia are found at the same time from the macro- 

 sporogonium and not by successive divisions. Thus the 

 individual Spermatobium transforms itself into a macro- 

 sporogonium, which later again divides into a number of 

 microsporogonia, each one containing a number of spo- 

 roblasts, consisting each one of cytospheres, cytosphero- 

 theca and micronuclei. Each sporoblast converts itself 

 into a lunate or shuttle spore. In each microsporogonium 

 we may find from forty to sixty sporoblasts or shuttle 

 spores, but generally very many less (figs.. 24 to 31). 



