38 



HARLEY N. GOULD 



latter does not lag far behind, however. Table 2 gives the rela- 

 tive conditions observed in the gonad, goniduct and penis of 

 animals assuming the male phase. 



TABLE 2 



Relative conditions in gonad, goniduct and penis of specimens undergoing male 

 development. Length of each specimen' s shell given in millimeters. The penis 

 has not reached its full development in any of the individuals, for by the time 

 that takes place the testis is fully mature and the seminal vesicle has increased 

 enormously and twisted upon itself many times. The great expansion of the 

 seminal vesicle is due to the pressure of the mass of sperm within; for it never 

 reaches a very large size until it is packed closely with sperm; and if it is emptied 

 of sperm there is a subsequent shrinkage. 



Contents of the seminal vesicle. As stated previously, both 

 eupyrene and apyrene sperm are found in the seminal vesicle 



