100 M. L. Plate on Ectoparasitic Rotatoria 



could be observed in it. The posterior division also contains 

 a finely granular mass, which, in general, does not completely 

 fill the space assigned to it, and also frequently shows vacuo- 

 liform clear spaces. It is certainly different in its structure 

 and nature from the substance of the head-piece. 



So long as we have not succeeded in observing the action 

 of the flasklets above described in the act of copulation we can 

 only form suppositions as to their nature. I regard them as 

 spermatojjhores which, under certain circumstances, set free 

 the portion of semen contained in their anterior division. 

 This opinion is supported by the following observation. Not 

 unfrequently we find in the hinder termination of the vasa 

 deferentia sperm-flasklets which have the anterior division 

 still empty, but which are placed in the immediate vicinity of 

 a mass of living spermatozoa, and therefore produce exactly 

 the impression that they are about to take in a number of the 

 latter. Unfortunately I did not notice whether such sperm- 

 flasklets are or are not furnished with substance in their pos- 

 terior cavity ; but in my preserved material I found a young 

 male with a spermatophore having no semen in the anterior, 

 but with contents in the posterior division. Probably, there- 

 fore, this is formed by a turgescible mass, which, when in the 

 body of the female, bursts the walls of the flasklet, and so 

 renders it possible for the spermatozoa to amalgamate with 

 the ova. The position which the spermatophores take up in 

 the male animal is worthy of note. They are all, both in the 

 ductus ejaculatorhis and in the vasa deferentia^ arranged more 

 or less parallel to the longitudinal axis of the male, and always 

 turn the head-end towards the posterior pole of the body of 

 the latter (fig. 13). Where and how they are produced I was 

 unable to ascertain, but they are certainly formed very early, 

 as perfectly developed sperm-flasklets are to be met with in 

 the interior of embryos still unhatched. 



No spermatophores or structures which can be compared 

 with these have hitherto been observed in the Rotatoria ; even 

 in Seison they do not appear to occur, — or are the small bacilli 

 which also show a clear middle part and dark anterior and 

 posterior divisions, and which, according to Glaus, densely 

 fill the ductus ejacidatorius and the terminal portion of the 

 vas deferens^ homologous although less perfect structures? 

 The male sexual apparatus of Seison^ however, differs con- 

 siderably from that above described. Thus its ductus ejacu- 

 latorius, as stated by the Viennese zoologist, possesses two 

 appendicular organs, a diverticulum on the right-hand side 

 and opposite this a multipartite glandular body ; further, the 

 same organ presents a wall furnished with strong muscula- 



