HISTORY OP THE ROTIFERA, OR WHEEL ANIMALCULES. 493 
and some are vomiting forth the flattened pale-yellow eggs 
which are ready in the ovary. This is, indeed, the first thing 
done as soon as a cluster is put into the live-box ; the animals 
being probably excited by being caught and moved from vessel 
to vessel. Many eggs are presently seen, forcibly expelled 
from different individuals and whirling about in front of the 
animals. (See figs, f, /, /.) Ehrenberg says, that in M. albo- 
flavicans they are attached to the parent by a thread for some 
time ; but in this case there is certainly no attachment : they 
are simply retained by the vortices of the ciliary currents. 
This was clearly shown in the case of one egg, which, on 
being ejected, for some cause or other, escaped being caught 
in the ciliary currents, and swam slowly away, with the original 
impulse, far out of the range of the parent. I did not trace the 
development of any of the eggs. 
The form of the egg is very peculiar : it appears to be nearly 
circular, flattened on one side and convex on the other ; there is 
considerable difference in their size ; they are of a pale-yellow 
hue, marked with several blackish specks. 
After having been some time, perhaps two or three hours, in 
the live-box, the animals begin, one by one, to separate them- 
selves from the group, and to swim off in freedom. The foot, 
immediately after separation, shrinks up so as to be little more 
than a thick nipple, and sometimes shrinks completely within 
the body, within which it is seen much shortened and corrugated; 
the body is also enlarged and turgid at the bottom. The ciliary 
motion now carries it rapidly along, revolving on its longitu- 
dinal axis, until it is brought to the margin of the box or to the 
edge of the flattened drop of water, along which it then swims in 
a backward direction, the foot foremost ; now and then it rapidly 
reverses its course, but invariably turns so as to keep the foot 
before. After pursuing this amusement a little while, it stops, 
becomes still ; the action of the cilia grows feeble and languid : 
these organs hang over the side of the coronal circle like flexible 
hooks ; the jaws cease to work, and the creature soon dissolves 
into a yellowish indistinct mass. I tried to feed them with 
indigo, sap-green, and carmine ; but though the pigment, after 
being whirled around the ciliary currents, accumulated in masses 
outside the cone, I could not perceive that a particle entered 
the body of any. 
The largest cluster that I examined, measured, when under 
the pressure of a compressor, about l-30th of an inch in diame- 
ter, and the longest extended animal l-50th. When the pres- 
sure was removed, these measurements were reduced respectively 
to l-36th and l-70th. An animal contracted in swimming 
independently was about 1-1 50th of an inch long. 
Professor Huxley has given a valuable account of the struc- 
