33 2 D. D. WHITNEY. 



determine the size and condition of the head of the spermatozoon 

 after it had entered the egg. The egg examined was sectioned 

 while inside the body of the female and although it had the thick 

 secretion around it which later would have shrunken to form the 

 heavy external covering or shell it was readily sectioned at this 



?&* 



-*- 



FIG. 6. Portion of a fertilized egg of Hydatina senta. E, egg nucleus containing 

 chromosomes; 5, sperm-head; Y, yolk granules of the egg. (Sperm-head and the 

 outline of egg nucleus drawn to same scale as in Figs. 3-5. Yolk granules and 

 chromosomes drawn freehand without measurements.) 



early stage. The sperm head is seen near the nucleus of the 

 egg (Fig. 6). It is about the size of the head of the normal 

 spermatozoon as can be seen by comparing it with Fig. 3, but 

 contains denser chromatin material and is perfectly round in 

 form. 



Dimorphic spermatozoa have been studied in considerable 

 detail in some of the Mollusca and in some of the Lepidoptera 

 by several workers. Among these Goldschmidt and Gatenby 

 recently have come to the conclusion that the atypical or abnor- 

 mal spermatozoa are wholly functionless and the latter is of the 

 opinion that such spermatozoa have no significance in regard to 

 sex regulation. According to their conclusion any spermatozoa 

 and in some cases all spermatozoa of these forms studied may 

 become degenerate if the male individual is in a certain physiologi- 

 cal condition. 



In the phylloxerans and in the rotifers the case is quite dif- 

 ferent. In each and every male a certain percentage of the sperm 



