REPRODUCTION' IX THE INFUSORIA. 185 



the parenchyma of the body. As many as fourteen or fifteen 

 distinct masses may be counted in the ovary of adult ex- 

 amples of Stentor. " In Spirostomum ambiguum and in Rhon- 

 chylostoma patens, other species belonging to the family of 

 Bursarina and allied to Stentor, the ovarian elements are still 

 further multiplied than in these last, and form, collectively, 

 a long band which, according as its divisions are more or less 

 distinctly indicated, presents sometimes an aspect simply 

 nodose, sometimes that of a bent chaplet made up of from 

 thirty to more than forty elements, extending without inter- 

 ruption throughout the entire length of the body. 



The number of male elements is usually equal to that of 

 the female, though, in rare cases, a multiple ovary coexists 

 with a simple testis, or the reverse arrangement may present 

 itself, as in Stylonychia mytilus and Urostyla Weissii, in which 

 each division of the bi-partite ovary supports a testis at either 

 of its two extremities. 



Before fission or sexual union, the elements of the sexual 

 apparatus may be observed to separate from one another, and 

 to a greater or less extent,' to change their previous position 

 within the interior of the body. 



The three kinds of reproductive apparatus above described 

 differ, as we have seen, in a marked degree from one another. 

 But the existence of many intermediate conditions, establish- 

 ing a gradual connection between one principal form and 

 another, forbids our drawing too absolute a line of demarca- 

 tion between them. Even the same infusorium, at different 

 periods of its existence, may exhibit all three of the modifica- 

 tions in question. The young individuals of Stentor have, 

 at first, a simple rounded ovary ; while, in adults of the same 

 genus, this oi'gan, as already mentioned, presents the aspect 

 of a beaded chaplet. Previous to each act of fission, how- 

 ever, the ovary assumes the second, or cylindrical form; a 

 fact which would seem to hold good in the case of all Infu- 

 soria, whether their female organ be simply ovoid or moni- 

 liform. Stentor Roeselii of Ehrenberg scarcely diSers from 

 St. Miilleri of the same author, save in the unarticulated 

 condition of its nucleus, a condition which, in this in- 

 stance, ]M. Balbiani asserts to be of a wholly transient na- 

 ture, and quite unworthy to be made the basis of a specific 

 distinction. On the other hand, those Infusoria in which the 

 simplest kind of reproductive apparatus exists exhibit a di- 

 vision of the nucleus into two (oi', it may be, more) parts, 

 about the time of sexual union, so that the chief diff'erence 

 between the ovary of such forms and of the Oxytrichina be- 



