488 



various other observers upon this part of the subject. He next men- 

 tioned appearances which he terms vacuolar thickenings, some of which 

 he stated to have been considered by Prof. Ehrenberg as ganglia, 

 others as testes, &c., but, in the author's opinion, erroneously, inas- 

 much as they appear to him to be merely local thickenings of the pa- 

 rietes in various parts of the body. The nervous system, or organs of 

 sense, were then described ; and some remarks on the reproductive 

 organs followed, in which some curious observations on the develop- 

 ment of the ova were given, showing that the process is exactly that 

 which takes place in all fecundated ova, and leading to the supposi- 

 tion that Spermatozoa should, somewhere or other, be found. He, 

 however, had not been able to satisfy himself of their existence, 

 although he had seen objects which answered precisely to Kollicher's 

 description of the Spermatozoa in Megalotrocha, and expressed his 

 opinion that it was impossible, in the present state of our knowledge, 

 to come to any definite conclusion upon the subject. He next pro- 

 ceeded to make some remarks on the asexual propagation of Lacinu- 

 laria and other Rotifera, in which he pointed out the difference 

 between the ordinary ova and those called " winter ova," which last 

 he proposes to call ephippial ova. The development and progress of 

 these last were very fully described ; and he concludes this part of the 

 subject by stating that "there are two kinds of reproductive bodies in 

 Lacinularia: 1st, Bodies which resemble true ova in their origin and 

 subsequent development, and w^hich possess only a single membrane ; 

 2ndly, Bodies half as large again as the foregoing, which resemble the 

 ephippium of Daphnia, like it, have altogether three investments, and 

 which do not resemble true ova, either in their origin or subsequent 

 development, which, therefore, probably do not require fecundation, 

 and are thence to be considered as a mode of asexual reproduction." 

 He then proceeded to make some remarks on the zoological position 

 of the Rotifera, as deduced from the structure of the Lacinularia, as 

 now described ; and, after pointing out that the relations between the 

 Polyzoa and the Rotifera were at the best only mere analogies, he 

 stated that the general agreement in structure between the Rotifera 

 and the Annuloida (under which term he includes the Annelidae, the 

 Echinoderms, the Trematoda;, Turbellaria, and Nematoideaj) is very 

 striking, and such as to constitute an unquestionable affinity. This 

 position he proved by numerous examples, and concluded by giving 

 a sketch of the affinities of the Annuloidaj, in which class he proposes 

 to place the Rotifera, thus removing them entirely from the class Ra- 

 diata of Cuvier, in which they have hitherto been included. 



