.'544 Miscellaneous. 



they are very long, have two long cilia at their anterior extremity, 

 and a very contractile plasma ; finally they penetrate into the jelly 

 surrounding the female cells or " oospheres," and the fusion of an 

 antherozoid and an oosphere gives origin to an ovum, which becomes 

 red in passing to the condition of latent life. 



In OJdamydomonas Iteinhardti the author has shown* that in 

 two cells which conjugate to form an ovum the nuclei become fused 

 together, and this is no doubt the case in Eudorina, although it has 

 not been observed directly. 



Besides the normal mode of formation of the antherozoids in 

 Eudorina the author has observed another which he thinks serves 

 to elucidate the value and signification of the sexual reproduction in 

 some Volvocinese. His observations were made in February upon 

 cultures of about six months. 



In a colony of 32 cells, when the division of the cells has advanced 

 to the 8- or 16-stage, as the division does not follow a parallel 

 course in all the cells, some will remain entire while others are 

 already divided into 2, 4, 8, or 1(3. The division completed these 

 cells arrange themselves as if to form an asexual colony, and then 

 the following phenomena were observed, here given in the order of 

 their occurrence. 



On Monday the colony presented two mother-colls, A and B, each 

 containing 10 elongated green antherozoids, moving briskly within 

 the cavity containing them. 



On Tuesday most of the antherozoids of A had escaped ; those of 

 B were still very active. In a third mother-cell, C, the still globular 

 daughter-cells arranged themselves in accordance with a spherical 

 surface and then began to move slowly within the cavity ; they were 

 green and possessed two cilia and a red point. 



On Wednesday the antherozoids of B escaped ; their plasma con- 

 tracted with great facility, and, except in their green colour, they 

 exactly resembled the ordinary antherozoids. In C the cells quick- 

 ened their movements and became more elongated in form ; in a 

 fourth mother-cell, D, the daughter-cells also began to move. 



The same phenomena occurred during the following days in each 

 cell of the colony. 



The author considers that these facts show clearly that in Eudorina 

 the formation of a disk is not a necessary preliminary to the produc- 

 tion of the antherozoids, but that green globular cells resembling 

 the vegetative cells and oospheres may directly give origin to anthe- 

 rozoids ; whence it follows that the sexual reproduction of. Eudorina, 

 and consequently of Volvos, is only an unimportant modification of 

 the isogamy which is known to occur in some Chlamydomonades, in 

 Chlorogonium, Pandorina, and Stephanosphcera. — Bull. Hoc. Linn. 

 Normandie, ser. 4, vol. ii. p. 124 (188!)). 



* Bull. Soc. Linn. Norm. 1887. 



