59 
ther the oxygen nor the hydrogen of which water is composed, nor the two applied 
together in mechanical mixture, as a gas, produce this effect in the slightest de¬ 
gree. Water also boils at 212°, and freezes at 32°, of the common thermometer, 
but neither of its two elements does this. As gases, the ultimate effect of boiling 
has passed upon them in bringing them to that state; and neither of them can be 
rendered solid, or even liquid, by any degree of cold with which we are ac¬ 
quainted. Innumerable instances, many of them far more striking than this, will 
occur to every one who has even a very slight acquaintance with chemistry, and 
also to any one who attends to the difference between the properties of mixtures, 
and those of the ingredients of which they are formed. 
The conclusion here is altogether irresistible; namely, that we cannot attribute 
any one property or phenomenon, of a material compound, to any one ingredient 
of that compound, to the exclusion of the rest. It is in the fact of being com¬ 
pounded that all the properties of the compound originate, and when the com¬ 
pound is dissolved all those properties are at an end. 
This illustration is taken from compounds which are not organized, and there¬ 
fore it is not exactly in point as applied to animals. But still it is the foundation upon 
which our judgment of animals must rest, and, consequently, we must admit 
into the organized and more complicated compound nothing which is inconsistent 
with it. In every part of its system the animal is matter, and therefore it must 
obey the laws of matter, in so far as those laws are not controlled by the power of 
organization in the animal; which is the fact of animal composition, and not a 
substance which could by possibility have a separate existence, or an existence in 
any other species of animal, or even in any other individual, than merely the one 
which was the immediate subject of the inquiry. 
Such being the case, we must be very careful, and not dogmatically attribute 
any function to any one structure of an animal, or even to any one organ, how 
necessary so ever that organ may be to the exercise of the function. Thus, for in¬ 
stance, an eye is absolutely necessary to the function of vision ; but still it would 
be most unphilosophical to say that an eye sees ; because, if such were the case, a 
dead eye, if in perfect preservation, ought to see as well as a living one. The 
very same argument applies to every organ in all the other systems. Nothing is 
more common, for instance, than the belief that animals perceive, and are impelled 
to act, by the brain; and there are not a few who assign different impulses to diffe¬ 
rent parts of this organ: but were this the case, an uninjured brain, separated 
from the rest of the animal, ought to be as “ cogitative” and “ volontative” as 
ever. 
But to leave this preliminary caution, which is a most essential one, especially 
to young naturalists, let us return to the organic systems which, in their combina¬ 
tion, make up the body of an animal, and observe how they are distributed in the 
two grand divisions of vertebrated and invertebrated—or skeletoned and skeleton- 
i 2 
