162 GENEEAL HISTORY OF THE INFUSORIA. 



frequently be seen to diminish as they pass backward among the female cells, 

 when their disappearance can only be accounted for by their having become 

 incorporated with the green cells. Eudorina in this stage also may frequently 

 be seen with all the four anterior cells absent, and only a few spermatozoids 

 left, most of which are motionless and adherent to the capsules, — indicating 

 that the rest have disappeared in the way mentioned. Lastly, many Eudorince 

 in this stage may be observed with not only the four anterior cells absent, but 

 with hardly a single spermatozoid left, — indicating that the whole had passed 

 into the female cells, or had become expended in the process of impregnation, 

 I have never seen any spermatozoids in the central or axial cavity, nor do I 

 think that there is a means of their escaping externally without rupture ; so 

 that their being confined to the space between the two ovoid cells of the Eu- 

 dorina, where the green cells are situated, is another reason, if any more be 

 needed, for considering them fecundating agents. 



" What changes take place in the Eudorina after this, I have not been able 

 to discover. At the time, the female cells appear to become more opake by 

 the incorporation of the spermatozoids ; and the crenulated state of the poste- 

 rior part of the envelope in this stage seems also to indicate an approach to 

 disintegration. I have also observed that those Eudorince which are under- 

 going, or apparently have undergone impregnation, are less active than the 

 rest, — that is, those in which the spermatozoids are scattered throughout the 

 interspace mentioned and applying themselves to the capsules of the green 

 cells, and those in which there are only a few spermatozoids left. But even 

 if they did become disintegrated, the latter, when free, would so closely re- 

 semble those of Chlamydococcus, which was also abundantly present, that un- 

 less the Eudorina could be found undergoing impregnation by itself, or apart 

 from this organism, there appears to me no chance of distinguishing the two, 

 and therefore no other means of completing this part of its history. It is 

 true that the impregnated cells may undergo some change in form similar to 

 those of Vohox glohator after impregnation ; but I think I should have seen this 

 among the numbers which came under my observation, if it had been the case. 



" While undergoing impregnation, the female cells always contain from 

 two to four nuclei, as if preparatory to the third stage of development, into 

 Avhich they are sometimes actually seen passing, Avith the spermatozoids pre- 

 sent and scattered among them ; but the effect of impregnation generally 

 seems to arrest this stage, and thus save the species from that minute divi- 

 sion which leads to the destructive termination of Eudorina already noticed. 



" Sometimes all the cells together imdergo the spermatoid fissuration, when 

 the Eudorina passes into Pandorina Morum, Ehr. ; but in this case the de- 

 velopment 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. As the groups, however, progress in de- 

 velopment, 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 Goni^nn, 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 only 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 appear. Ehren- 

 berg was wrong in giving the cells of Pandorina and Eudori7ia single cilia, as 

 has before been stated, and partly wrong in leaving out the eye-spot, both 



