494 
POPULAR SCIENCE REVIEW. 
ture and economy of M. ( Lacinularia ) socialis.* He finds the 
clusters of this species abundantly studding the leaves of Cera- 
tophyllum, which grows in the Medway, near Farleigh Bridge. 
In general appearance and habits this species agrees with the 
one I have just described ; the animals, however, are more 
slender, and the distinction between the body and the foot is less 
strongly marked. The eggs are of the ordinary form, not of 
the remarkable turban-like shape of those of 21. volvox ; they 
are laid in the cells of the gelatinous sphere, where they are 
hatched. Here the young five for a while; but as soon as 
the disk begins to assume a triangular outline, and the foot 
to be developed, they “ begin to ‘ swarm/ uniting themselves 
by their caudal extremities, and are readily pressed out as 
united free-swimming colonies, resembling, in this state,” the 
previous species. Ehrenberg says that seven or eight eggs are 
deposited in each cell; that these form a new cluster, swim 
away, and form an envelope of their own, but that, when only 
one is born, it attaches itself to the side of its parent. We 
may inquire how the young clusters of six or seven (and the 
young of one parent accumulated in the case at one time 
could never greatly exceed this number) increase to forty or 
more. Perhaps this last fact may help to guide our conjec- 
tures. Probably, as the individual young grow in size, the 
interspaces left between them, becoming’ wider, afford ample 
room for intruders ; and the new progeny of these, as they 
are hatched, at once take their place, one by one, in the 
parent sphere, swelling its bulk up to the dimensions of matu- 
rity ; and that the swarming does not begin to occur till these 
dimensions are attained. The free- swimming’ swarms are tem- 
porarily in the condition which in M. volvox is permanent, and 
may readily be supposed (as has, indeed, been done) to consti- 
tute a distinct species. As the Berlin Professor observes, 
“ They have not yet the character of the genus [species], but 
are Lacvnularice notwithstanding, as young frogs without feet, 
and with gills and tails, must still remain frogs.” 
Professor Huxley has discovered that another form of eggs, 
which he compares with the ephippial eggs of some of the 
water-fleas ( Daphnia , &c.), is produced by M. socialis. They 
are inclosed in a double investing membrane, the inner of which 
sends off a partition that divides the contents into two equal 
portions. Cohn, however, believes that these are not proper 
eggs, but gemmce, having analogy to the buds of a plant, while 
eggs are analogous to its seeds. New plants may be grown 
from either; but, physiologically, the plant produced from a 
bud or cutting is only a severed and independent part of the 
* “ Trans. Micr. Soc,,” 1853. 
