Volvoceae 



179 



2, 4, 8, etc., until a large number of cells are produced forming a spherical 

 young colony. All these cells are included within the periphery of the 

 enlarged wall of the mother-cell, which rapidly becomes converted into a firm 

 jelly. As gelatinization of the wall proceeds the young cells, although still 

 dividing, become spaced further apart. The daughter-coenobia project into 

 the cavity of the mother-coenobium and finally become quite free within this 

 cavity ultimately escaping into the surrounding water by the rupture and 

 death of the parent. In the various species of Volvox three generations of 

 individuals can often be seen within one another; and in V. africanus, in which 

 the daughter-coenobia grow to a large size and become compressed before 

 being set free, four generations can be distinctly observed (G. S. W., '10). 





Fig. 107. A and B, Platydorina caudata Kofoid, x 420. A, colony seen from the flat side; 

 B, seen from the edge. C, Stephanoon Askenasii Schewk., individual with 16 cells, x 600. 

 (A and B, after Kofoid ; C, after Schevviakoff, from Wille.) p.s, outer firm mucilaginous 

 envelope ; s.sh, secondary mucilaginous coat around each cell. 



Powers ('05) states that in V. Weismanniana many of the young colonies 

 are completely everted (i.e. turned inside out) during their development. 

 ' The process begins at various periods before the closing of the young colony 

 and is finally completed by a reclosure of the colony, the surfaces of which 

 arc now reversed, at a somewhat later period.' 



122 



