308 



D. D. WHITNEY. 



able that many of these males had already paired with females 

 and consequently had shed some of their spermatozoa. This 

 would explain the variability of the spermatozoa counts in the 

 first twenty-one males recorded in Table I. 



TABLE I. 



Brachionus mulleri. Showing the relative proportional number of the two kinds 

 of spermatozoa found in each testis of thirty male individuals. The rudi- 

 mentary spermatozoa were never found as numerous as the functional sperm- 

 atozoa in any testis of a young male. In the immature males in which none 

 of the spermatozoa had been fully formed or shed the larger spermatids that 

 ultimately develop into the functional spermatozoa were found to be exactly 

 twice as numerous as the smaller spermatids that ultimately develop into the 

 rudimentary spermatozoa. 



When immature males were crushed one could readily count 

 all the spermatids of both kinds and could definitely determine 

 the relative number of each. It was seen at once when all 

 spermatids were counted that the two kinds of spermatids that 

 develop into the two kinds of spermatozoa did not occur in equal 

 numbers. The large spermatids which ultimately develop into 

 the large motile spermatozoa were found to be exactly twice as 

 numerous as the smaller spermatids which ultimately develop 

 into the small spindle-shaped spermatozoa. This is clearly 

 shown in the last few males recorded in Table I. Figs. I and 2 



