PRODUCTION OF SPERMATOZOA IN ROTIFERS. 3! I 



two kinds of spermatozoa were found and the larger motile 

 ones were more numerous than the smaller immotile ones. 

 Drawings of these spermatozoa are shown in Figs. 4, 6, 7, 8, 9 

 and 10. 



Morgan has found in the study of the spermatogenesis of some 

 of the phylloxerans that the secondary spermatocytes are of two 

 kinds the normal and the rudimentary. The normal sperma- 

 tocytes divide again to form the spermatids, each of which 

 develops later into a functional spermatozoon. The rudimentary 

 spermatocytes do not divide again and do not form spermatids 

 or spermatozoa. They merely persist for a time as rudimentary 

 secondary spermatocytes and then finally disintegrate and dis- 

 appear. Morgan has also found the same phenomenon in some 

 of the aphids, Stevens and von Baehr have also found it in the 

 aphids, Meves has found it in Vespa germanica, Mark and Cope- 

 land have found it in Vespa maculata, and Lams has found it in 

 an ant, Campodinotus herculaneus. 



In the grand total count of all the spermatocytes and sperma- 

 tids at the end of the final spermatocyte divisions in all of these 

 forms enumerated in the preceding paragraph the normal sperma- 

 tids should have been twice as numerous as the rudimentary 

 spermatocytes. No counts, however, were made and conse- 

 quently this point was not settled by this method but it was 

 demonstrated in another manner by showing that only one 

 spermatocyte division occurred in the rudimentary sperma- 

 tocytes and two divisions occurred in the normal sperma- 

 tocytes in the process of formation of the normal spermatozoa. 

 In 1909 Morgan said in regard to the rotifer, Hydatina senta, 

 which at the time had not been investigated. 'Theoretically 

 there should not be two spermatocyte divisions but only one true 

 division. It remains to be seen whether this prediction proves 

 true." 



The rotifers have not only fulfilled but have exceeded Morgan's 

 expectations ! They not only produce normal spermatids and rudi- 

 mentary secondary spermatocytes in the ratio of 2 : 1 as probably 

 do these forms already mentioned, but they develop both of these 

 into spermatozoa which are later shed by the males. Those of 

 one kind are large, motile and probably functional while those of 



