Development of Rotifer vulgaris. 147 



cules, which appeared to me to be attached (connected) from 

 without, that supported me in my notion of a sexual form of 

 reproduction in Rotifer, although I should have been at a 

 loss to indicate in this group of animals any organ which 

 presumably might have the function of a male sexual gland. 



The objections of Prof, von Stein to any other view than 

 that in the present case we have to do only with Trypano- 

 coccuSj are certainly of great weight. Nevertheless the matter 

 is not yet fully elucidated, and it is of the greatest interest 

 that all naturalists who occupy themselves seriously with the 

 anatomy of the Rotatoria should look out for the presence of 

 Trypanococcus, by which means we may by degrees obtain 

 more accurate information as to the history of the reproduction 

 of this remarkable Jnfusory. 



For the elucidation of the question of egg-gemmation it 

 would also of course be of great importance if Prof. Ganin 

 would have the kindness to give further details of his obser- 

 vations, made in the year 1871, upon Callklina parasitica. 

 He has no doubt already done this in no. 6 of the ' Trans- 

 actions of the University of Warsaw,' but the memoir in 

 question is written in Russian, and therefore not generally 

 accessible. 



With regard to the reproduction of Rotifer vulgaris I have 

 therefore only been able once more to confirm the long-known 

 fact that it takes place parthenogenetically . That besides the 

 ovarian eggs, which are developed without previous fecundation, 

 others are from time to time produced (by gemmation) which 

 undergo fecundation, is rendered very doubtful by what Prof, 

 von Stein has objected against my observations. Whether 

 the previous observations of Prof. Ganin, which certainly 

 seem to be in favour of a second kind of egg-formation in 

 Philodinidse, are really so well founded as to exclude all 

 doubt, I am unable to judge. As already said, it is very 

 desirable Prof. Ganin should speak out upon this point. 



The subject under consideration is both biologically and 

 physiologically of the greatest possible importance. 



EXPLANATION OF PLATE V. B. 



(A selection of figures from the author's plate. The original 

 numbers are indicated in brackets.) 



Fig. 1 [1]. An adult example of Rotifer vulgaris, seen from the ventral 

 surface. Auf, eye-spots, shining through ; ro, rotatory organ j 

 gs, grey substance (salivary glands ?) ; z, paired cells ; ha, masti- 

 catory apparatus ; dr, stomachal glands ; i, inner membrane of 

 the intestine ; eg, excretory system of vessels ; zo, tremulous 

 organs (ciliated funnels) ; ov, ovary, with an ovum in course of 

 constriction ; cbl, contractile vesicle : fdr, pedal gland ; fe, pro- 

 trusible extremity of the foot. 



