MOVEMENTS OF THE SPERMATOZOA. 151 



have already corroborated his statement in Man, the Hedgehog, 

 Dog, Guinea-pig, Rabbit, Frog, and Triton,* and Kolliker-f also 

 concurs in its accuracy. I have not always been able in appa- 

 rently mature spermatozoa to perceive the line of demarcation 

 between the intermediate piece and the tail, and must there- 

 fore refer to an investigation of the semen obtained from the 

 female genitals. An opportunity for pursuing this inquiry offered 

 itself to me in a Bat that had been isolated for thirty-six hours. 

 Both the vagina and uterus were here filled with spermatozoa 

 in lively movement, all of which exhibited a very distinct inter- 

 mediate portion. The length of this intermediate portion varies, 

 according to Schweigger-Seidel, between 9 and 23 /i ; in Man 

 it amounts to 6 p. 



MOVEMENTS OF THE SPERMATOZOA. As I have already 

 remarked, in a few animals the spermatozoa are perfectly 

 motionless, even when within the female generative organs ; 

 ex. gr., Oniscus : in others we find indications of motility in the 

 occurrence of amoeboid changes of form, as in the Nematode 

 worms (Schneider), Daphnia (Ley dig), Crabs (Owsjannikow). 

 The greater number of the different kinds of spermatozoa are, 

 however, capable of performing a very considerable amount 

 of locomotion. These are materially assisted by the action 

 of the above-described undulating membranes. The movement 

 may consist in a regular and progressive advance, as in the 

 spermatozoa of the Canary, where the whole spermatozoon 

 rotates extremely rapidly on its axis; or it may present a 

 leaping or convulsive character, as in Mammals. Between these 

 extremes there are all conceivable variations : where it is 

 distinctly marked, the capitate extremity always goes first. 

 Grohe believes that the movement is initiated by the contrac- 

 tion of the contents, which, however, with Schweigger-Seidel 

 and Kolliker, I consider to be doubtful. I have never been 

 able to distinguish any movements of this kind in the head, 

 though headless tails may often be seen in lively vibration. I 

 must also demur to the statement of Schweigger-Seidel, that 

 the intermediate portion is rigid, and takes no part in the move- 



* Max Schultze's Archiv. 1867, Band iii., p. 264. t Loc. cit., p. 530. 



