SPERMATOZOA MINGLED WITH OVA. 175 



fact that there were sometimes spermatozoa seemed 

 beyond dispute ; Kolliker had seen them, and asserted 

 them to be as numerous as ova. The solution of the 

 difficulty dawned upon me when I discovered that the 

 spermatozoa were contained in vesicles, so like ova in 

 the early stage as to be easily mistaken for them. It is 

 only by crushing these that the spermatozoa are seen 

 escaping. Thus it became inteUigible that I might 

 have had spermatic vesicles in the ovaries under obser- 

 vation, where I thought there were only ova ; and all 

 my females might have been hermaphrodite. Unhappily 

 this clue was detected at a period when I was so deeply 

 engrossed with the nervous system of the Mollusca, 

 that I had little time to devote to the unravelling of 

 the whole mystery. But I made a few direct and con- 

 clusive observations, which assured me that ova and 

 spermatozoa were intermingled in the same stroma ; 

 and the student may easily verify these observations 

 when informed that the ova are distinguishable from 

 the spermatic vesicles by their darker colour ; he has 

 only to spread out, on a glass slide, a fold of the mem- 

 brane containing the ova, and he will perceive among 

 them polyhedral and oval bodies of a paler colour : if 

 these are crushed, the spermatozoa will be seen escap- 

 ing from them. 



How can this be reconciled with Kolliker's and 

 HoUard's statement of the sexes being separate ? If I 

 could have devoted the requisite time to the point, 

 when specimens were abundant, I might, perhaps, 

 have answered positively what I can now only answer 



