380 Some Account of the Meduse 
results, by the observation of several thousands of medusee 
of various kinds collected in different seas. 
Now we may venture to ask physiologists, how they can 
conceive that so many eminent characters, that so much 
order and regularity, can belong exclusively to this same 
-system of locomotion, which in all the other families of 
animals seems to require from nature, and to have actually 
received from her, the greatest mobility in its principle, the 
greatest anomaly in its developments, the greatest inde- 
pendence and versatility in its immediate agents? How 
can we in fairness refuse to acknowledge the numerous 
characters which we have indicated, a true system of gene- 
_tal contractibility, the locomotion of which is in truth one 
of the most sensible results, but which seems to belong in 
a still more important manner to the very essence of the 
life of the medusz ? 
If, in short, we glance at the numerous series of beings 
which compose the animal kingdom, we soon find that, 
whatever may be the differences of forms and of organi- 
zation which they affect, all of them have nevertheless a 
certain number of common functions, without the union 
of which their existence would be as it were impossible 
to conceive. In the more perfect animals, each of these 
grand functions has its peculiar seat, its distinct organs, 
and particular laws; but this could not be the case with 
those anomalous species on which nature seems in a great 
measure to have attempted some huge animal creations : 
the singular substance of these less perfect species, the 
homogencousness of their texture, the simplicity of their 
organization, reduced to the first element of life, every 
thing in them opposes the distinction, and above all the 
multiplicity of the organs. Subordinate from that. mo- 
ment to common agents, the functions most essential to 
existence may be easily mistaken; because they are con- 
founded in their effects, as in the principle which deter- 
mines them, and which supports them. 
This principle seems to be, in the meduse, the very con- 
tractibility in question. Who is there, in fact, who ean- 
not see bow favourable these motions, so continuous and 
so regular, of systole and diastole, are to the circulation of 
liquids in the most delicate vessels of the umbrella? How 
greatly do they aid digestion and nutrition! How great is. 
their influence over the abundant secretions just men- 
tioned! Elow great, in short, is their analogy with these 
movements of inspiration and expiration, which are oat 
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