THE PRINCIPLE OF VITAL AFFINITY. 313 



and hydrogen are thrown off in carbonic acid and water. Thus, supposing a large 

 quantity of starch, 60 C, 50 H, 50 0, to unite with a small quantity of ammonia, 

 we have 



C N H 



60 6 68 50 and adding 20 of oxygen, 

 we have 60 6 68 70=48 C, 6 N, 36 H, 14 0, 



(the elements of albumen) + 32 HO + 12 COo, the water and carbonic acid which 

 escape. Or, adding an equivalent of oil, we may have 



C N H 



48 ... 40 40 Starch. 

 Add 12 ... 10 1 Oil. 



6 18 ••• Ammonia. 



60 6 68 41 



Subtract 48 6 36 14 Albumen. 



12 - 32 27 Adding 29 oxygen, 

 we get 12 CO. + 32 HO carbonic acid and water. 



It is certain, therefore, that if the elements of ammonia can be set free in 

 the primse vise of an animal, starch absorbed from thence, with or without the 

 addition of oil, may be converted into albumen in its blood, without any other 

 matter being thrown off than the water and carbonic acid, which undoubtedly 

 escape from every animal. If this be so, we have here another division of the ele- 

 ments of the ingesta, between substances exerting a vital and a simply chemical 

 affinity for them, and another formation of part of the excretions, by the help of 

 the oxygen of the air, from matters recently absorbed, and which aid in the nou- 

 rishment of the animal. But whether this is a process that actually goes on in 

 the animal economy, or whether all the albuminous compounds of animal bodies 

 have passed into them, directly or indirectly (but ready formed), from vegetables, 

 is the point at this moment the most important to be ascertained. 



As it is obvious that the albuminous compounds, and the gelatinous compounds 

 (which are closely related to them, and are generally thought to be formed from 

 them), compose the greater part of the animal textures, and are equally the ground- 

 work of aU animal structure, as starch is of vegetables, this inquiry involves the 

 essential point of distinction, so far as chemistry goes, between vegetables and 

 animals. It is well known that both Liebig and Dumas have expressed a de- 

 cided opinion that no albumen is formed in animals ; and the latter author has 

 contrasted, in a lively manner, vegetable and animal life in this respect, repre- 

 senting the former as always a reducing or deoxidating apparatus, and the latter 

 as an apparatus of oxidation or combustion, i. e., of the destruction, never of the 

 formation, of any organic compound. But he does not appear to have adverted 

 particularly to the question which seems to me the most essential in a physiolo- 

 gical view, viz., what are the chemical changes during the state of life, whether 



VOL. XVI. PART III. 4 K 



