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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- 



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