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ternal warmth. Hence it is to be inferred, that the identity of a 

 living principle, at least among the animals which afterwards dis- 

 play the possession of vital heat, is not perfected but by the in- 

 fluence of heat.* 



9. As processes of life are commenced by the influence of 

 heat, as heat and life are invariable accompaniments, the one not 

 ceasing as long as the other continues; but more especially as the 

 vitality of the egg is no more than a predisposition to the living 

 state, and as heat perfects it in this state and afterwards remains 

 with it; we must infer from these facts, as well by general consent in 

 matters of reasoning as in consonance with the laws of causation, 

 that heat is an essential property belonging to the common living 

 principle; that heat unites with the other properties of life, which, 

 in the egg, were before only predisponent, and that the identity 

 of life is thus conjointly produced. 



10. It has been shewn that life is so related with its elements 

 in the material, as to be able by uniting them to produce its own 

 resemblance, which has been called assimilation. Now if life has 

 an assimilative relation with the elements, heat being a part of life, 

 is also maintained in the same way; that original heat which was 

 Conferred on, or belonged to, the life of the ovum, is that which, 

 continuing with it and growing with it, afterwards maintains, in 

 conjunction with it, the phenomena of animal heat; no circum- 

 stances of which are not explicable by a reference to this union in 

 its regular or modified conditions. 



11. That heat, like the other properties of life, is maintained 

 by assimilation, is shewn by the same proofs as those which esta- 

 blish this mode, as belonging to the general principle. The proofs 

 may be enumerated as follows: 1st, the chymical and mechanical 

 parts of an animal, life being extinct, become rapidly cold ; they 

 therefore have no relation among their agents, which will produce 

 heat; 2nd, life exempt from heat (as in the ovum, &c.) cannot 

 produce heat, though subjected to the same substances in other 

 respects; 3rd, heat united to the living principle produces heat. 

 The first proves that the composition of the structures cannot 

 produce heat; the second, that the other properties of life cannot 

 produce it; the third, that it is instrumental to its own production. 

 This seems tolerably clear. 



12. But the relation of the heat forming a part of the spirit, 

 is not simply with its own elements, for heat conferred artificially 

 upon dead textures, although the same elements be exposed to it, 

 will not be produced, any more than life will be produced without 

 heat. 



13. Hence it follows, that the relation between heat and the 

 other properties of life is this, namely, there is an affinity between 



* That certain forms of life operate without heat, or but an inconsiderable 

 decree of it, as among cold-blooded animals, and vegetables, proves only that 

 life, existing in different forma, has its peculiar efficacy, dependencies, and 

 relations, respectively in each. 



