68 COCCOPHYCE^E. 



Fandorina morum. E7ir. Inf. p. 53, t. IT. f. 33. 



Coenobium globose. Cells green, 16-32, arranged about the 

 periphery. In the forms which produce the resting spores, the 

 cells are crowded together in the centre. Resting spores after 

 becoming encysted bright red. 



SIZE. Ccenobium "2 mm. Cells -01--015 mm. diam. 



Rabh. Alg. Eur. iii. 99. Henfrey Micr. Trans. (1856) p. 

 49, t. 4. Pringsheim Monatsb. Berlin, Oct., 1869. Ann. 

 Nat. Hist. v. (1870) p. 272. Pritchard Infus. pp. 157 and 517, 

 t. xix. fig. 59-69. Braun Rejuv. pp. 169-209. 



In standing water. 



" Fronds hyaline from about 1-80" downwards. Gonidia either 16, 

 and then arranged in four circles of 4, or 32 and then in five circles, two 

 at the poles of 4, and the intermediate three of 8 gonidia, which in the 

 perfect form stand near the periphery, and wide apart. In the forms 

 which produce the resting spores the gonidia are crowded together in 

 the centre. The gonidia are green, but the contents of the resting 

 spores, after they have become encysted, are converted into oily and 

 granular matter of a bright red colour." Henfrmj. 



Pringsheim, in his memoir "on the pairing of Zoospores,"* makes 

 special reference to this species. He says that asexual reproduction 

 takes place in Pandorina, as in other multicellular Volvocineae, by the 

 formation of a perfect young plant in each cell of the mother plant. By 

 the gradual dissolution of the general envelope and of the special mem- 

 brane of the mother-cells, the young plants become free, and escape. In 

 sexual reproduction, as in the asexual, the membrane of the old plant 

 swells, and sixteen young plants are formed. The young plants, how- 

 ever, are (at least in part) not neuter, but sexual, and either male or 

 female. Whether the mother plant is monoecious or dioecious is difficult to 

 determine, because the male and female plants are externally alike, and 

 can hardly be distinguished with certainty during copulation. There is 

 no striking difference in structure between the sexual and asexual 

 plants, although, amongst the former, plants with less than sixteen cells, 

 especially with eight cells, are oftener produced. Moreover, the dissolu- 

 tion of the membrane of the mother-cell proceeds more slowly than in 

 the case of neuter plants, one result of which is that the young asexual 

 plants vary much in the extent of their growth, and continue united in 

 groups of different sizes for a long time after their formation, according 

 as a greater or less number of them have happened to become free from 

 the gelatinous mass in which they were embedded. 



As the individual groups are at first motionless, and the mother plant 

 loses its cilia during the formation of the young ones, the entire group 

 is at first entirely quiescent. But afterwards the young sexual plants, 

 like the neuter ones, produce upon each of their cells two cilia, which 

 commence their motion as soon as the enveloping mucus admits of it, 

 and thus ultimately the entire group assumes a state of active rota- 

 tion. During the rotation of the groups the same process of expan- 

 sion and dissolution takes place in the membrane of the sexual plants 

 as occurred in the mother plant ; but the contents of the cells of the 

 Bexual plants do not undergo division, but combine to form a single 

 zoospore, which becomes free by the rapid dissolution of the mem- 

 branes. In their general structure these zoospores differ in no way 



* Monatsbericht, Eoy. Acad. Sciences, Berlin, Oct.. 1869. Translated 

 in "Annals of Natural History," Vol. V. (1870), p. 272. 



