^ 



On the ffeneralive Organs anil Produits of Tomopteris onihciformis E. 433 



observed. The sizes «>f the sues vary eonsiderably. The rounded 

 forms seen in Kig. 5 are on an average about 0,0775 mm in diameter, 

 while others may be as much as 0,124 mm in length and 0,02 mm 

 or even less in breadth. The shape and size of the seminal vesicles 

 depend on the amount of the contents and on the peristaltic move- 

 ments of the intestine in the caudal prolongation. 



T he s p e r m a 1 z o a which crowd into the seminal vesicles are 

 easily recognised both in the living animal and in the specimens 

 mounted whole and in serial section, Figs. 6 — 9 sp. Carpentkh A: 

 CLAi'.\id:DE describe correctly the spermatozoa in the vesicle as "in 

 continual movement upon each other, the motion being kept up chiefly, 

 if not entirely, by the action of the cilia clothing that part of the 

 inner wall which is near its external orifice''. The ciliary action doubt- 

 less extends much beyond the external orifice, and the ceaseless peri- 

 staltic motions of the intestine also help to promote the movements 

 among the contents of the vesicle, as well as the vibratile lashings 

 of the tails of the spermatozoa. The sperms, which are set free from 

 the cells arising in the forks of the parapodia, can be seen in the body- 

 cavity of the mature male, and Vejdovsky has described their entrance 

 into his "Samenleiter". The head of the spermatozoon is ovate, but 1 did 

 not see that it was furnished with more than one tail, and it is pos- 

 sible that Caiitenter a: ClaparI'.de may be correct in describing it as 

 l)ossessed of two tails. The head-portion ranges from 0,004 to 0,005 mm 

 in its greatest diameter, and the lesser diameter is about half of this. 

 They stain much more deeply after treatment with carmine than do 

 any other cells of the body. 



The male genital orifices are two in number, one from 

 the seminal vesicle to the exterior, Figs. 5, 6, 7, 8 v. s.o., and the 

 second opens into the body-cavity. Figs 6 a', 9 v.s.i. 



The external opening is easily seen in those where the spermato- 

 zoa are not crowded in the seminal vesicle quite up to the opening. 

 In many, especially where the vesicles are nearly spherical, a clear 

 liyaline space is left around the external aperture, Fig. 5 v. s. o., and 

 on closer inspection at the apex of this space a small circular collar, 

 Fig. 7, is seen bounding the very small aperture, v. s.o. This hyaline 

 space is only seen plainly in preserved and stained specimens. 

 Sections reveal its presence also. Fig. 8 v. s. o. The inner opening is 

 not so easily .seen in mounted specimens. This is doubtless due to 

 the great contraction w hich takes place , and the absence in most of 

 spermatozoa at this portion of the canal. But occasionally in sections, 



