PRODUCTION OF SPERMATOZOA IN ROTIFERS. 



309 



show a series of the various stages of development from early 

 spermatids to mature spermatozoa of both kinds of these di- 

 morphic spermatozoa. 



Mature males of Hydatina senta were crushed and examined 

 and were found also to possess the two kinds of spermatozoa as 

 markedly dimorphic as those in Brachionus mulleri. Many 

 more spermatozoa are formed in the testis and consequently 

 the counts could not be. as readily or as accurately made as in 

 Brachionus mulleri. Counts enough, however, were made to 

 show that the large motile spermatozoa were about twice as 

 numerous as the smaller immotile spindle-shaped spermatozoa. 



B 



FIG. 2. Formation of the rudimentary spermatozoa in Brachionus mulleri. 

 A, young spermatids; B, older spermatids; C, young immature spermatozoa; 

 D, mature, immotile, and rudimentary spermatozoa. 



The counts are shown in Table II. and drawings of the two kinds 

 of spermatozoa are shown in Fig. 5. 



The spermatozoa were examined next of the large viviparous 

 rotifer, Asplanchna amphora, and although no very accurate 

 counts could be made the two kinds of spermatozoa were con- 



