66 COCCOPHYCE^E. 



divisions it is probable that many of the groups, if they do not form new 

 individuals, sooner or later become disintegrated, and the Eudorina, thus 

 eventually perishes. 



When, however, the process of impregnation takes place, the division 

 stops at the second stage, that is when the Eudorina consists of 32 cells 

 of the largest kind, each of which is about !-18<i6th of an inch in dia- 

 meter within its capsule, which is therefore a little larger. The process 

 is as follows : 



At a certain period after the second stage has become fully developed 

 the contents of the four anterior cells respectively present lines of dupli- 

 cative subdivision, which radiate from a point in the posterior part of the 

 cell (in the subdivision of other cells the lines of fissiparation tend 

 towards the centre of the cell). These lines, which ultimately divide 

 the green contents of the cell into 64 portions, where the division stops, 

 entail a pyriform shape on the segments, from whose extremities a mass 

 of cilia may be observed waving in the anterior part of the cell of the 

 parent, while yet her own pair of cilia are in active motion, and her eye- 

 spot still exists in situ on one side of her progeny, thus showing that the 

 latter may be almost fully formed before the parent perishes. At length, 

 however, this takes place, and the progeny (Spermatozoids) separate from 

 each other, and finding an exit, probably by rupture, through the effete 

 parent cell and her capsule, soon become dispersed throughout the space 

 between the two large ovoid cells mentioned, where they thus freely come 

 into contact with the capsules of the twenty-eight remaining, or female 

 cells. 



The form of the spermatozoid now varies at every instant from the 

 activity of its movements, and the almost semifluid state of its plasma. 

 Its changes, however, are confined to elongation and contraction ; hence 

 it is sometimes linear-fusiform, or lunular, at others pyriform, short, or 

 elongate. The centre of the body is tinged green by the presence of a 

 little chlorophyll, while the extremities are colourless, the anterior one 

 bears a pair of cilia, and there is an eye-spot a little in front of the middle 

 of the body, also probably a nucleus. It is about l-2700th of an inch 

 long and about one-fifth as broad. 



Once in the space mentioned, the spermatozoids soon find their way 

 among the female cells to the capsules, of which they apply themselves 

 most vigorously and pertinaciously, flattening, elongating, and changing 

 themselves into various forms as they glide over their surfaces, until they 

 find a point of ingress, when they appear to slip in, and, coming in con- 

 tact with the female cell, to sink into her substance as by amalgamation. 

 This author explains that there was some difficult)' in seeing the act of 

 union, but of the act itself he entertained no doubts. 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 Eudorinu; in this stage may be observed 

 with not only the four anterior cells absent, but with hardly a spermato- 

 zoid left, indicating that the whole had passed into the female cells or 

 had become expended in the process of impregnation. 



What changes take place in the Eudorina after this he had not been 

 able to discover. At the time the female cells appear to become more 

 opaque by the incorporation of the spermatozoids, and the crenulated 

 state of the posterior part of the envelope in this stage seems also to in- 

 dicate an approach to disintegration. 



While undergoing impregnation the female cells always contain from 

 2 to 4 nuclei, as if preparatory to the third stage of development into 

 which they are sometimes actually seen passing, with the spermatozoids 

 present and scattered among them ; but the effect of impregnation 

 generally seems to arrest this stage, and thus save the species from 

 that minute division which leads to destruction. 



