in Eudorina elegans and Cryptoglena. 249 



one which could furnish the double spore-cell and smaller gonidia 

 in large numbers, while in most instances the split lorica still 

 adhered to the internal cell as a mark of identification, no doubt 

 could be entertained that both the large and the small gonidia 

 belonged to the same organism, that their coming together 

 under such circumstances could only be for the purpose of 

 fecundation, and that they therefore were the female cells and 

 spermatozoids of this species. 



I therefore watched the motions of the spermatozoids so situ- 

 ated, in two or three instances for more than half an hour to- 

 gether, during which time they dashed themselves against the 

 cell, adhered to it, retreated from and advanced upon it, with 

 unabated rapidity, but without penetrating it, — when, having 

 little time left, comparatively, for such observations, I sought 

 out group after group quickly, without watching it long at a 

 time, until I had the good fortune to find one in which, after a 

 moment's watching, one of the spermatozoids appeared within 

 the cell, and, fixing itself to one of the spores or female cells, 

 gradually became incorporated with it (fig. 26). This was suf- 

 ficient to convince me of the fact I had anticipated ; but it would 

 have been more satisfactory to have seen it repeated, and pro- 

 bably I might have done so had the fecundating process in the 

 colony been prolonged : but it only lasted three days after I 

 first discovered it, and during that time I had little leisure 

 to devote to the subject; for to be successful in researches of 

 this kind requires uninterrupted observation for long periods 

 together. However, had I not even seen the incorporation, no 

 other interpretation could be given to the facts mentioned than 

 that they were connected with the process of fecundation. 



I have stated that the cell containing the two gonidia was the 

 one invariably surrounded by the spermatozoids ; but it was not 

 the only one, for in two or three instances a few were found 

 around and adhering to the inner cell of the four- division (fig. 21) 

 after liberation, indicating that the gonidia of this division were 

 also sought after by the spermatozoids, if even in the end they 

 did not become reproductive. It was also observed that the two- 

 division did not always come forth in one cell, but that some- 

 times this was also divided, so that each gonidium had its proper 

 cell (fig. 27). 



The form of the macrogonidia or female cells did not differ 

 from the internal cell of the parent, except in being a little 

 smaller, — while the microgonidium, which was not more than 

 l-7th of the diameter of the macrogonidium, and therefore very 

 small, appeared, though equally green and provided with an 

 eye-spot, to have only one cilium. I cannot help thinking, 

 however, that, with a higher power, I might have seen two. 



