3B 
Busk oii Volvox glohator. 
2. That the contents of this apparently nucleated discoid 
cell, consisting of a grumous material and refractive amyla- 
ceous (?) spherules, after a time undergo segmentation, at 
the same time exhibiting a distinct wall, beyond which is a 
delicate areola, apparently of a gelatinous consistence. 
3. That this segmentation, attended with a corresponding 
augmentation in the number of the refractive spherules, ter- 
minates ultimately in the formation of numerous contiguous 
particles or segments. 
4. That these ultimate segments are gradually separated 
from each other, remaining connected only by elongated pro- 
cesses or filaments, and constituting the ciliated zoospores of 
the mature Volvox. 
5. That these zoospores at first are simple masses of pro- 
toplasm, containing a transparent nuclear body, and that 
afterwards they present for a time clear, circular spaces, which 
contract rhythmically at regular^intervals ; and are subsequently 
furnished with a brown eye-spot ; and at a very early period 
with two long retractile cilia, which, arising from an elongated 
hyaline beak, penetrate the parent cell-wall, and exert active 
movements external to it. 
6. That in a concentric plane internal to these ciliated zoo- 
spores are placed the germs of future individuals destined to 
follow the same course. 
fiaving thus traced one form of Volvox through its course of 
development, I will proceed much more briefly to the others. 
In V. aureus, as I have said, the constitution of the wall of 
the parent cell is exactly as above described. At its earliest 
appearance also the internal embryonic body cannot be dis- 
tinguished from that of the ordinary form, except in its deeper 
green colour. It afterwards, however, acquires a thick wall, 
changes its colour to yellow without material alteration in size, 
and acquires a second equally firm and distinct envelope, or 
rather, as I believe, the original contents contract somewhat, 
and then form a second coat around themselves. Eventually 
a considerable space exists between these two coats (figs. 
10, 12), which space is occupied by a clear and apparently 
aqueous fluid, but upon the addition of a solution of iodine a 
granular cloudiness is produced in this fluid. The contents of 
the inner cell consist chiefly of amylaceous grains mixed with 
a greenish material in the one case, and with a bright yellow 
apparently oily fluid in the other. The amylaceous particles 
are of an irregular botryoidal form, and far from uniform in 
size. As regards the future destination of this form of germ, 
I am as yet in total ignorance ; there can, however, I think, be 
little doubt but that it represents the " still " form of spore of 
