
THE PRINCIPLE OF VITAL AFFINITY. 311 
that the one is a change which uniformly results when the sugar is exposed to 
the influence of air, water, and a certain temperature ; and is in contact with a sub- 
stance undergoing some part of that decomposition and chemical change to which 
living bodies are liable after the phenomena of life are over ; whereas the other is 
not seen, in the presence of those substances, and under those conditions as to air, 
water, and temperature, in which it here takes place, unless the starch is at the 
same time in contact with living cells,—. ¢., cells forming a part of a body in 
which the peculiar phenomena of life are then exhibited.* 
II. The next question is as to the formation of the Albuminous, or what have 
lately been called the Protein, compounds in animal bodies. The late acrimoni- 
ous dispute as to the existence of Protein, should rather be termed a dispute as to 
the exact composition of the compound to which MuLDER gave that name, and 
which is thrown down from the solution of either albumen or fibrin, in potash. 
by acetic acid. Of the precipitate being the same in both cases there is no doubt: 
and we shall avoid the controversy entirely, by using the term Albuminous Com- 
pounds, as Dr Prout did, instead of the term Protein. 
Since it has been clearly ascertained, that the vegetable gluten is identical 
in composition with the albuminous compounds,—~. ¢., fibrin, albumen, and ca- 
sein of animals,—no doubt can exist that the formation of a great part of the al- 
bumen found in animal bodies must take place in vegetables; and, I presume, it 
is also generally agreed that the chief agents in this farther change, beyond the 
formation of starch and of fat, are sulphur, and ammonia or its elements, taken 
into the fiuids of the vegetable, although it is still doubtful from what sources 
this ammonia or its elements may be originally derived, and particularly whether. 
in any circumstances, the azote of the atmosphere is concerned in producing it. 
Some experiments recorded by Dumas,t however, seem to leave no room for 
doubt, that certain families of plants, in one way or another, fix azote from the 
air, being found to add largely to that contained in their seeds, when ger- 
minating and growing merely in silica and water; and it is by no means as- 
certained, that this azote passes necessarily into the state of ammonia be- 
fore it is applied to the nourishment of those vegetables. And the state- 
ments of MULDER seem equally conclusive as to the fact, that ammonia may be 
* It is no objection to this statement, that oily matters may, in different cases besides that of 
adipocere already noticed, be formed from organic compounds in the dead state, 7. e., by simply chemi- 
cal affinities. To establish that the affinity by which it is formed in a living structure is vital, it is 
not necessary to shew that oil cannot be formed, under any circumstances, by simply chemical laws, but 
only to assure ourselves, that it cannot be formed by those laws from the substances, and in the circum- 
stances, in which it is continually formed in certain living cells. 
+ Balance of Organic Nature, p. 77. 
