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586 SUPPLEMENT 
and of an areolar tissue, as it were spongy, susceptible of a 
sort of erection by the introduction of an aqueous fluid; a 
body with which is in organic communication a considerable 
number of little animals, each having a buccal orifice, sur- 
rounded with a rank of pennated tentacula, and an oviferous 
sac, developed in the tissue itself of the pennatula. 
The physiological phenomena which the pennatula pre- 
sents is extremely interesting, since it exhibits the example 
of a truly composite animal, that is, one in which animals, more 
or less in number, really perfect as far as comports with the 
grade of organization to which they belong, form part of a 
common, living, contractile body, serving as an intermedium 
both for locomotion and nutrition to all the individuals, so 
that they are all carried together by the sole movements of 
the common part, without the particular movements of each 
occasioning any obstacle, and they are all nourished in a 
mediate manner, by means of this common portion of which 
they form a part. The nutriment which favourable circum- 
stances have placed within the reach of one individual, 
nourishes that individual first, and then by extension, 
nourishes the common stem, and thus the other polypi, which 
constitute organic portions of it, receive their share. 
It is rather more difficult to conceive the mode of growth 
in the pennatula, and its mode of reproduction. In all the 
aggregate polyparia, as the madrepores, the growth proceeds 
by the extremities, and consequently, very probably, by the 
adherence of the gemmules, produced by the terminal polypi, 
to the lodge of the latter. The accidental fall of these gem- 
mules gives birth to new individuals. In the first case, we 
must consider it rather an accumulation, than a true growth ; 
and, in fact, there is a real death of all that is below the ex- 
tremities. It cannot be so in the pennatula, which is a ter- 
minated and finished whole, so that we must believe that the 
growth here is really individual, at least in the common part. 
