330 DR ALISON'S OBSERVATIONS ON 



bonic acid. " There exists," says Liebig, " in every compound a statical momen- 

 tum {moment statique) of the attractive powers which combine the elements ; 

 the inertia of the elementary atoms, or their disposition to persist in the same 

 state, or in the same place, where they actually exist, acts there as a special 

 force. If the atoms of sugar were held together by as strong a force as the 

 elements of sulphate of potass, they would suffer as little disturbance as these, 

 from the presence of a ferment or a putrescent body. But this is not the case. 

 The elements of all organic compounds which are capable of undergoing transfor- 

 mations preserve their condition only in virtue of the inertia, which is one of 

 their properties."'* 



Again, it has been reasonably objected to the doctrine of the nutrition and 

 growth of animals being due to an affinity between their textures and the in- 

 gesta taken into them, which ceases when these ingesta lose their vitality, that 

 these aliments are very generally in a dead state before they are submitted to 

 the organs of digestion.f But I apprehend the proper answer to this to be, 

 that, — so far as the chemical phenomena of life are concerned, the death of an 

 entire living structure is quite distinct from the death of any one of its com- 

 ponent parts. The Avhole of a living structure dies when its nutrition, the most 

 essential of its functions, is brought to a stand by the failure of circulation ; but 

 the organic compounds, formed, as I believe, by vital affinities in that structure, 

 remain for very various periods of time unaltered, or are preserved, as Liebig 

 expresses it, by the inertia of matter, from forming those inorganic compounds 

 to which they are ultimately destined ; and as long as they remain //-es/i, or, al- 

 though undergoing decomposition, have not yet reverted to those inorganic com- 

 pounds, they seem to be still capable of being acted on by the vital affinities of 

 animals. But, when the simply chemical affinities have really resumed their 

 power, when a part of the body has undergone a certain degree of putrefaction, — 

 when the carbon of these compounds has passed into the state of carbonic acid, — or 

 even when this and the other elements have combined so as to form the excretions, 

 which are steps in the process by which they revert to carbonic acid, water, and 

 ammonia, — they are no longer capable of being applied to the nutrition of animal 

 bodies, untU they have been again subjected to the influence of vegetable life. 

 The fact of their falling into the combinations which form the excretions, in the 

 act of absorption from the living textures, must be regarded as proof that they 

 have lost then- own living properties, and can no longer form part of a living 

 texture, although still within a living structure. This death of the individual 

 molecules forming the living textures, I take to be the counterpart of the conti- 

 nued nutrition of those textures during life, as a general fact in the history of 



* " Sur les Phenomenes de la Fermentation," &c. Annales de Chimie, t. Ixxi., p. 19, 193. 

 I See the Review of Prout's 4th edition, in British and Foreign Review. 



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