882 RECORD OF CURRENT RESEARCHES RELATING TO 



ventral side and posteriorly to tlie moutli appear two important 

 organs ; tlie hinder pair consist of two setae, eacli of wliicli lies in a 

 cellular sac, which is apparently its matrix ; in front of these there 

 is a pair of extremely delicate tubes which jjroject freely into the 

 ccelom, and are covered by epithelium and by a peritoneal investment ; 

 they have a narrow, although distinct, lumen. Unable to give any 

 account of these orifices, the author regards them as primitive seg- 

 mental organs ; they disappear very soon. As to the generative 

 organs, the ovaries appear very early in the form of large cells, with 

 round nuclei, placed near the hinder portion of the ventral vessel. 



Tlie ilfaZe.— The history of the male of Bonellia is one of the most 

 interesting in comparative anatomy ; Schmarda, regarding the funnel 

 of the uterus as the testis, considered that Bonellia was herma- 

 phrodite. Lacaze-Duthiers considered that all the specimens he had 

 seen were females, and Kowalevsky was of the same opinion, until in 

 1868 he found in the female ducts a number of small Planarian-liko 

 parasites, which he regarded as being the male form of this interesting 

 creature. In 1877 Vejdovsky discovered (and in 1878 gave an account 

 of his observations *) the ventral nerve-cord ; Selenka has reported 

 the presence of two sub-oesophageal ganglia and of a pair of segmental 

 organs ; while, on the other hand, Greef has lately expressed his 

 dissatisfaction as to the reality of this Planarioid form being the male 

 of Bonellia. 



Dr. Spengel found the males forming green scales on the pro- 

 boscis of the female, and they, when, after some difficulty, separated 

 from it, exhibited themselves under the form of elongated small worms 

 with a green coloured epidermis, two eyes at their anterior end, and 

 an oily euteron — in fine they ajipeared to be Bonellia-larvce, save 

 only that they had lost their two bands of cilia. Further inves- 

 tigation showed that they possessed germ-cells, altogether similar to 

 those of the female, connected with masses of somewhat smaller cells, 

 arranged in a central and a peripheral group ; the latter are the true 

 seminal cells ; increasing in size, they become separated from the 

 surrounding tissue and swim about in the body-cavity of the males. 

 Meantime the mesoderm in the anterior region becomes more compact, 

 the rudiments of the oesophagus disappear, and the hinder portion 

 of the enteric tract becomes fused with the mesoderm. 



It is impossible here to enter into the details of the organization 

 of the male, and we must refer in a very few words to their " morpho- 

 logy." The anterior portion of the body represents the " cephalic 

 lobes" of the female, the ventral cord is essentially the same as it 

 is in the asexual larva, but the cellular elements are not, as in the 

 female, arranged metamerically ; they form a connected cord ; the 

 digestive system is in a very elementary condition. No vascular 

 system ajipears to be developed, but this is probably due to the 

 mesodermal cells going completely to form the sperm. In conclu- 

 sion, it is observed that the male of Bonellia is a Gephyrean in 

 all essential points, and that, subsequently to the larval stages, all 

 interest is centred on the male organs, while the loss of the ciliated 

 * See this Journal, ante. p. 290. 



