462 GENERAL HISTOKY OF THE rNFTJSOSIA. 



From the above remarks and statements, it seems to us quite clear that 

 the pyramidal sac opening into the cloaca, and its upwardly-prolonged canals 

 referred to, are nothing more than the *' water-vascular system " of the Me- 

 licerta, and that more or fewer of the observed vibratile bodies are, in fact, 

 the ciliated tremulous tags. Had the pyramidal sac represented a testicle, 

 spermatozoa ought to have been seen within it ; for these particles are readily 

 cognizable by their size, figure, and movements. 



Prof. Huxley having failed to find a male among some scores of female 

 Lacinularice, or a single ordinary spennatozoon, is disposed to recognize the 

 male sexual element in some singular bodies met with in many individuals he 

 examined. These bodies '^ answered precisely to Kolliker's description of 

 the spermatozoa " of Megalotrocha. They had a pyramidal head about y^-n-th 

 of an inch in diameter, by wliich they were attached to the parietes of the 

 body, and an appendage foiu^ times as long, which underwent the most ex- 

 traordinary contortions, — resembling, however, a vibrating membrane much 

 more than the tail of a spermatozoon, as the undulating motion appeared to 

 take place on only one side of the appendage, which was zigzagged, while the 

 other remained smooth. *' According to Kolliker, again, these bodies are 

 found only in those animals which possess ova undergoing the process of 

 yelk- division, while I found them as frequently in those young forms which 

 had not yet developed ova, but only possessed an ovary. 



" Are these bodies spermatozoa ? Against this view we have the unques- 

 tionable separation of the sexes in Notommata, and the very great difference 

 between them and the spermatozoa of Notommata. Neither the mode of de- 

 velopment, nor the changes undergone by the ovum, afford any certain test 

 that it requires or has suffered fecundation, inasmuch as the process closely 

 resembles the original development of the Aphides. 



** In the view that Kollil?;er's bodies are true spermatozoa, it might be said, 

 1. That the sexes are united in most Distomata, for instance, and separated 

 in species closely allied (e. g. D. Ohenii). 2. That the differences between 

 these bodies and the spermatozoa of Notommata, is not greater than the dif- 

 ference between those of Tritons and those of Rana. 3. That their develop- 

 ment from nucleated cells within the body of MegaJotroclia (according to 

 Kolliker) is strong evidence as to their having some function to perform ; 

 and it is difficult to imagine what that can be if it be not that of spermatozoa. 

 However, it seems to me impossible to come to any definite conclusion upon 

 the subject at present." 



In Melicerta, Prof. Huxley notes having met with " an oval sac lying below 

 the ovary, and containing a number of strongly-refracting particles, closely 

 resembling in size and form the heads of the spermatozoa of Lacinularia.^' 



These views of Mr. Huxley are of no value in deciding the question ; they 

 rest on a supposed similarity between the bodies discovered and those which 

 Kolliker behoved to be spermatozoa in Megalatrocha, — an opinion not incon- 

 trovertible. On the other hand, their spermatozoid nature is discountenanced 

 by their similarity (which, indeed, Huxley remarks) to undoubted sperma- 

 tozoa of Rotifera. 



In a new species of Melicerta discovered by Prof. Bailey in America, that 

 accurate observer found that pressure between two plates of glass hberated 

 vast numbers of spermatozoa ; but he was unable to ascertain from what 

 organ in the animal they were set free. The observation, however, is im- 

 portant as indicating the existence of true male organs in Melicerta of a Yeiy 

 different character from those suggested by various observers as having pos- 

 sibly fecundating functions. 



Respecting these questionable male elements, Leydig has the following 



