6 Mr. H. J. Carter on Fecundation in the two Volvoces, 



the peripheral cells, which thus projects into the interior of the 

 parent, and begins to undergo duplicative subdivision almost 

 immediately, that is, at the time when it does not exceed three 

 times the diameter of the peripheral cells. (Here is the great 

 point of difference between this and the daughters of Volvox 

 glohator, to which I have alluded.) As the daughter increases 

 in size, the duplicative subdivision goes on until a little before 

 it has reached its full development, when the cilia begin to be 

 developed, the pellicle hardens into the cell-wall, leaving holes 

 for the cilia, as before stated, and the young Volvox, thus be- 

 coming separated from its capsule, begins to rotate, — when the 

 parent Volvox, as well as the capsule, breaking down, the daughter 

 is liberated — though, as in Volvox glohator, not before the next 

 generation has become visible (PI. I. fig. 5). 



Fecundation. — Sometimes, instead of the eight daughters pro- 

 ducing eight grand-daughters, and thus passing into the com- 

 mon form just described, two, three, and not unfrequently all 

 the eight daughters may present an enlargement of eighty to a 

 hundred of their peripheral cells, indiscriminately scattered over 

 the posterior three-fourths of their spheres respectively (fig. 9) . 

 These cells, which are twice or thrice the size of the rest, and of a 

 light yellowish-green colour while the daughters remain within the 

 parent, become still more enlarged and of a deep-green colour a 

 short time after they have left her ; but before this takes place 

 to its full extent, four or more of them become larger than the 

 rest (fig. 9 &, b, b, b), and at the same time undergo duplicative 

 subdivision until they have respectively passed into 128 (?) 

 linear, ciliated segments, which are ultimately arranged vertically 

 upon the same plane, in a circular, tabular group, with their 

 cilia upwards ; and when the latter are sufficiently developed, 

 the group oscillates and rotates by their aid, both upon its long 

 and short axis (fig. 10 a, b). These are the spermatozoids, which, 

 when fully developed, separate, burst through their capsule into 

 the cavity of the daughter-cell, and apply themselves vigorously 

 to the other cells, which are the spores, and with which, accord- 

 ing to Cohn, they become incorporated. Each spermatozoid 

 may now be observed to be linear, horn-shaped, longer than that 

 of Volvox globator, with the attenuated part, which is colourless, 

 anteriorly, and the posterior part greenish from the presence of 

 a little chlorophyll, — provided with two cilia, which are attached 

 to the middle of the body, and, just opposite them, an eye-spot 

 (fig. 9 d). During progression they have a vermicular motion, 

 while their cilia float backwards ; and when upon the spore, their 

 elongated beak keeps up an incessant undulation, sometimes 

 getting into that position which has induced Cohn to compare 

 it to the " neck of a swan /' but a nearer similitude would be 



