242 Mr. H. J. Carter on Fecundation 



that minute division which leads to the destructive termination 

 of Eudorina already noticed. 



Sometimes all the cells together undergo the spermatoid 

 fissuration, when the Eudorina passes into Pandorina Morum, 

 Ehr. ; but in this case the development does not stop at the 

 pyriform spermatozoids, but goes on to the development of 

 thirty-two larger globular cells in each group, similar to those 

 produced in the third stage of Eudorina above described, when 

 they assume respectively a dome-shaped form, held together by 

 a membrane which is fixed to the point in the posterior extremity 

 of the cell from which the lines of fissiparation first radiated 

 (fig. 8). As the groups, however, progress in development, this 

 dome appears to become flatter, and, the Eudorina breaking up, 

 as in the third stage, these groups, when liberated, finally appear 

 to pass into the form of Gonium, when I think they perish, like 

 the corresponding groups of the third stage. I did not observe 

 this development (in which may be included some abnormal 

 states, where one or two of the spermatic cells fail, and one or 

 more of the female cells take on this mode of fissiparation 

 irregularly) until the normal one of impregnation ceased to ap- 

 pear. Ehrenberg was wrong in giving the cells of Pandorina 

 and Eudorina single cilia, as has before been stated ; and partly 

 wrong in leaving out the eye-spot ; both of which, though dis- 

 appearing ultimately, indicate the continued life of the parent- 

 cell, as in the development of the spermatozoids, long after the 

 formation of her progeny. 



Thus the process of impregnation in Eudorina agrees closely 

 with that described by Dr. F. Colin in Volvox globator, in which 

 organism I had seen some of the cells of the interior undergoing 

 a spermatoid development exactly like that above described, and 

 also that previously figured by Mr. Busk*, and alluded to by 

 him as one of * microgonidia f f and therefore the moment I 

 perceived it in Eudorina, in connexion with Dr. Cohn's announce- 

 ment, I felt convinced that the latter was right, and that I had 

 before me Eudorina also undergoing a similar process of fecun- 

 dation. 



So much for the spermatoid development ; let us now return 

 to that of the Eudorina in totality, concerning which there is 

 still an interesting question for our consideration, bearing on the 

 early development of this organism, which I have already stated 

 my inability to supply, viz. how does the sixteen-division of the 

 cell in the third stage of development take place, so as to allow 

 the cilia to become external ? It will be remembered that this 

 cell in the second stage, before it passes into the sixteen-division 

 of the third stage, consists of its capsule or cell-wall and the 

 * hoc. cit. pi. 5. fig. 14. t Id. p. 45. 



