MAMMALIA. 



No matter how high, according to an estimate, the 

 animal may be in the scale, the action of the animal 

 still belongs to matter, and may mingle with and be 

 blended and lost in the general mass of material 

 action, just as the substantive matter which composes 

 the body of the animal may, in whole after death, or 

 gradually and successively during life, be blended 

 with and lose in the general mass of substantive 

 matter. It is evident from the facts, and it ought to 

 be distinctly understood, that animal life, or animal 

 power, or whatever we may call that which evolves 

 an animal from its embryo, brings it to perfection, 

 and ultimately renders it up to mingle with the dust, 

 merely acts upon matter, but has no knowledge of 

 matter in that sense in which we speak of know- 

 ledge as the only demonstrative attribute of mind. 



We have a proof of this in the daily economy of 

 our own bodies : when we are young and increasing 

 in size, there is of course an addition to our frame of 

 all those different kinds of matter that enter into the 

 composition of the parts which are increased. But 

 we have in ourselves no knowledge that this is going 

 on ; and even at the period of our lives when our ; 

 increase in bodily volume is most rapid, we have no 

 knowledge that we are growing. So, also, throughout 

 the whole period of life, when matter unfit for living 

 action is removed, and new matter introduced to 

 supply its place, we have not the least knowledge of 

 what occurs ; and though it is probable that in the 

 course of a very few years the whole matter of the body 

 is removed and replaced by new matter, we are not in 

 the least aware of the occurrence even of the oue or 

 of the other. Now, if in our animal system we have no 

 knowledge of the matter which ministers to our growth, 

 or that which repairs the waste of our system, it 

 would be contrary to all the principles of reason 

 and judgment to suppose that, considered as ani- 

 mals, we could have any knowledge of matter or 

 its actions or changes, external of our own bodies. 



Thus what we actually feel in ourselves is quite 

 sufficient to guide our judgment in drawing the dis- 

 tinction between mental and animal action, and 

 enabling us to give full scope to our animal physio- 

 logy, without allowing it in the least to interfere with 

 the physiology of mind. We can no more give a 

 specific description of the animal power, than we 

 can do of the mental power, for we know nothing 

 about powers of any kind, farther than what we see 

 in the effects which they produce ; but we know 

 that the animal power invariably acts upon matter 

 without having any knowledge of matter ; while 

 the mental power knows matter without having any 

 capacity of acting upon matter, and this is a sufficient 

 distinction. 



But although the animal, or the power or energy 

 which exists in the animal, is inscrutable to our senses, 

 and we cannot describe it as we describe material 

 existence, yet we cannot help believing of it that it 

 is mortal, capable of existing only for a limited time 

 in one organisation which it elaborates for itself; and 

 when it is as it were exhausted and worn out in the 

 individual by the continual struggle which it main- 

 tains with the physical properties of matter during its 

 life, it must pass again through the embryo state, and 

 appear a new creature, though identical with and spe- 

 cies of the parent. This limit, which ties it down to the 

 species, we can no more understand than we can un- 

 derstand why there are specific differences in inani- 

 mate and inorganic matter ; but we can observe the 



fact in both cases, and it is as determinate in the one 

 as in the other. 



Although, therefore, our consideration of animal 

 physiology is entirely separated from the physiology 

 of mind, and shown to be totally different from it in 

 its nature, even in the human subject, in which the 

 two exist in combination ; yet we require to advert 

 to very different causes in the physiology of animals 

 from any 'which we meet with in the philosophy of 

 inorganic matter. In the last, the causes which we 

 have to consider are all physical ; but in the other 

 they are what may be called final; that is, causes 

 which are to be inferred from the purpose which 

 their operation accomplishes. The animal is a sort of 

 warfare against the common laws of nature in mere 

 matter : it grows in opposition to those laws, and it 

 lives and performs its functions in opposition to them ; 

 so that in the study of it we have to advert to assi- 

 milating and conserving faculties, which have nothing 

 to do with the physical operations of matter, whether 

 mechanical or chemical. The temporary or mortal 

 power of the animal is proved by the fact, that it can 

 maintain this warfare against the common laws of 

 matter only for a time ; and though this time is very 

 different in different species of animals, we cannot 

 predicate immortality of it in any one particular case. 

 It is not found except where there is both a com- 

 bination of matter and an organisation of matter ; 

 that is, a distribution of matter in a particular form, 

 which it would not assume were it not for the prin- 

 ciple of animal life ; and therefore, though during 

 the exercise of this principle, the merely mechanical 

 and chemical powers of matter are subdued, the prin- 

 ciple of animal life is so intimately connected with 

 matter, that it is impossible to separate the one from 

 the other. 



We must allow that there is not only a general 

 principle of animalisation, but that there are as many 

 distinctions or diversities of this principle dependent 

 on itself, as there are species of animals in the world ; 

 because we find that the line of distinction between 

 species and species cannot be broken. But while we 

 admit this, we must also admit that the laws of matter 

 exercise their power upon the material substance of 

 animals in the exact proportion that the animal power 

 allows them so to operate. There is no capacity in 

 the one to originate the other ; and as an animal can- 

 not create matter, or change the nature or form of 

 elementary matter, so neither can matter of itself 

 originate any animal how simple soever. In every 

 case there is an embryo, an alimentary animal being 

 wanted, and it is not a little remarkable, or confirm- 

 atory of the principle for which we are arguing, that 

 the care of this embryo, and the connexion which it 

 has with an antecedent animal life, are always in pro- 

 portion to the development of animal energy, or the 

 deviation of the animal considered as a piece of 

 matter from the common mass of inanimate matter of 

 which the globe is composed. In all cases there is 

 a certain dependence upon the parent. This de- 

 pendence is more brief and slight in some cases, and 

 more durable and intimate in others ; but in no in- 

 stance with which we are acquainted is there a new 

 animal life produced without some assistance from a 

 parent animal. 



When we look at the different classes into which 

 systematic naturalists divide the animal kingdom, we 

 find very remarkable proofs of this. In those which 

 have the least development and exercise of the sensa- 



