A Contrìbut. to the Embiyol., Life-history, and Classificat. of the Dicyemids. 59 



frequently made. I bave met with only tour instances. Aprii 8, I found 

 iu a large D. moschatum^ coiitaiuiug vermiform embryos, an euigmatic 

 ciliated body, resembling in shape and size an Infusoriform. I could 

 distiuguish the outlines of only a few cells. Aprii 9 I obtained another 

 individuai of the same kind (4mmlong'), in which, just behind the 

 single free nucleus , a similar body was found. In this case I could 

 distinguish plainly six cells , and the resemblance to an Infusoriform 

 was so dose that I no longer hesitated to regard it as such. Again on 

 Aprii 12, I found two of these bodies within the same Nematogen; and 

 under the same cover was another individuai in which there was only 

 one such body. In ali these cases the bodies were uudoubtedly modified 

 forms of Infnsoriforms. These four Dicyemids were ali obtained from 

 small Eledones , in which most of the parasites were Nematogenic. I 

 was unable , except in one case , to deterraine whether the axial cell 

 contained more thau one free nucleus. The Cephalopod^< were killed 

 by cutting off the head , and the examinations made immediately , so 

 that I am perfectly certain that I had fresh Dicyemids. I am also 

 equally certain that these Infusoriforms did not originate in the individ- 

 uals in which they were found, but had penetrated from without, and 

 were fast undergoing alterations , the precise nature of which I could 

 not ascertain. It is possible that such occurrences are not so rare as they 

 now appear to be ; and that they have*been overlooked either because 

 they are seasonal, or confined to young Cephalopods. If the Infusori- 

 forms be males, then a very probable explanation could be found for 

 these occurrences , and, further, for the fact before noticed, that Ne- 

 matogenic individuai» prevali in young Cephalopods. The species would 

 be carried to new hosts by the vermiform embryos ; and after a certain 

 number of parthenogenetic generations, or simultaneously with the fe- 

 males, would arrive the males. The males would penetrate the females, 

 the ova be fecundated, and a generation of vermiform embryos arise, 

 which would develop into diphygenic individuals. This is , to be sure, 

 ali conjecture; but it is nevertheless one of the possibilities which it 

 may be advantageous to keep in mind in future investigation of this 

 matter. If, however, there is no fecundation, or if it precede the elinii- 

 nation of the paranucleus, then it would be necessary to regard the tìve 

 Infusoriforms found in four Nematogenic individuals, as stragglers. 



T h e I n f u s r i g e n. — If the Infusorigen represents an individuai , 

 as I am strongly persuaded , then it must be regarded not only as a 

 form brought about by arrest of development , but also as one whose 

 personality and independence bave been largely sacriticed in the 



