438 Miscellaneous. 



gonidium, the parenchyma with the nuclear fragments, are seen to 

 pass slowly into the body of the large individual and mix with its 

 substance. The microgonidium is then reduced to its external en- 

 velope, empty and folded together; and this latter also at length 

 penetrates to the interior of the other individual, where it disappears 

 without leaving any trace. 



After mingling in the body of the individual resulting from the 

 conjugation, the fragments of the two nuclei approach one another, 

 and are fused into a common mass, to which M. Stein gives the name 

 of placenta. In the centre of this mass appear nucleated spheres 

 (Keimkugelri), which, in their turn, produce in their interior mobile 

 bodies furnished with vibratile cilia, which M. Stein regards as 

 the embryos of the Carchesium pohjpinum. These embryos escape 

 from, the mother by a special canal of parturition, while the un- 

 employed portion of the placenta lengthens and reconstitutes the 

 nucleus. 



Such is, in few words, the manner in which M. Stein describes the 

 reproduction of Carchesium and of several other Vorticcllians which 

 presented analogous phenomena. This description, indeed, presents 

 some considerable differences from that which I have given of the 

 sexual reproduction in the other Infusoria. It will be remarked, 

 above all, that there is no mention of the nucleolus, to which I ascribe 

 so important a part in this latter mode of multiplication, since, ac- 

 cording to me, it represents the male organ or testis of the Infusoria. 

 And, in fact, not only does M. Stein deny the existence of the 

 nucleus in all the Vorticcllians, but in them he expressly attributes 

 the formation of the germinative spheres and of the embryos 

 which proceed from them to the copulation of the nuclear frag- 

 ments of different origin, a copulation which he interprets as a true 

 fecundation. 



If things really occurred as M. Stein asserts, it would be neces- 

 sary to suppose one of two things — either the Vorticcllians are re- 

 produced in accordance with other laws than those which govern 

 the other Infusoria, or else my observations are not correct. The 

 absence of a fecundation by filiform spermatozoids originating in the 

 nucleolus, would, above all, establish between them a difference of 

 the first importance. I hasten to say that there is nothing of the 

 kind. It is a long time since I described and figured the nucleolus 

 in several Vorticellians, amongst which is Carchesium polypinum ; 

 and my observations on that subject have been confirmed by M. 

 Engelmann. 



I can only confirm all that M. Stein says of the formation of the 

 small individuals or microgonidia by successive binary divisions of a 

 single animalcule. I have seen, like him, these little products of 

 division abandon, one at a time, their common peduncle, and, after 

 a few moments of brisk agitation in the liquid, enter into conjuga- 

 tion with the sedentary individuals. This conjugation is not effected 

 without a certain resistance on the part of these latter, if we may 

 judge from the quick contractions of their peduncle at each contact of 



