io6 Chodat . — On the Polymorphism of the Green 
The origin of the thirty-two cells of the coenobium of 
Eudorina is the same as in Pandorina ; we have here merely 
the larval stage more advanced in division, following the same 
law. By degrees the thirty-two cells thus formed group 
together into an ellipsoid, which at first is open at one end. 
Up to the adult condition this origin is still apparent, the two 
poles being different. Non-sexual reproduction by the 
formation of a coenobium of four to eight cells arranged as in 
Pandoidna, viz. close to one another and not surrounding 
a gelatinous body, is very often produced in our cultivations. 
. These may be easily distinguished from P andorina by the 
mode of attachment of the cilia and the more globular shape 
of the cells. 
The origin of a Volvox-colony is quite the same 1 . The 
larval-condition is here still more pronounced than in the 
others; but owing to the greater specialization of the indivi- 
duals composing such a colony, the polymorphism is less 
marked. A unicellular stage is up to the present unknown. 
Thus considered, the Volvocineae constitute a very natural 
group in which the prevailing tendency is to replace the 
resting-stage of similar Palmellaceaeby the motile condition. 
The evolution of the group can be followed step by step. As 
has been demonstrated in Chlamydomonas , we can trace two 
different lines of development ; one has a tendency to retain 
the unicellular condition, the other to form a more or less 
complicated colony. 
The possibility of an indefinite variation in Chlamydomonas 
is also very clearly shown by the variability of the cell- 
contents, which are very uniform in the other Volvocineae, 
and still more in the different forms of sexuality found in this 
genus. Isogamy, heterogamy, and conjugation 2 3 have been 
observed ; whilst from the isogamous Chlamydomonas or 
isogamous Gonium 3 to the very highly differentiated anthero- 
1 See Kirchner, Stein und Klein, in Pringsheim’s Jahrb. f. Wiss. Bot. XX, and 
in Cohn’s Beitr. zur Biolog. III. 
2 Gorochankin, loc. cit. 
3 Chodat, Materiaux, I, p. 59 7. 
