I 



THE PRINCIPLE OF VITAL AFFINITY. 309 



formed from starch, or by which its elements are held together, does not super- 

 sede its natm-al chemical relations, but only adds a new chemical power to 

 those which can operate on it, and allows of a division of the starch between 

 the result of a vital and a simply chemical affinity; and, 2. That the vital 

 action by which fat is formed or maintained, is of no great strength, as com- 

 pared with the simply chemical affinities to which the same matter is liable ; 

 being superseded simply by an increased supply of oxygen. And we cannot 

 doubt that, in this as in other vital chemical processes, the oxygen, although 

 not taken into the organic compound formed, aids its formation materially, by pro- 

 moting, on the principle of divellent affinity, the other parts of the metamorphoses 

 whereby it is produced. We shall see afterwards the importance of having it esta- 

 blished by this simple example, that the oxygen of the air, when taken in full quan- 

 tity into the blood, is capable of combining, somewhere in the course of the circula- 

 tion with a part of that carbon and hydrogen, recently absorbed into the blood, 

 which, under a smaller supply of oxygen, would form a living texture ; and that 

 the combination of these portions of the ingesta M'ith oxygen, are one source of 

 the excretions. 



There are other facts which lead to the same conclusion, as to the affinity by 

 which fat is formed, being more nearly akin than most vital actions to simply 

 chemical affinities ; particularly, — 



1. The foi-mation of Adipocere, not from starch, but" from albumen, after 

 vitality is over, when undergoing decomposition under ground, where there is a 

 full supply of water and but little air, so that the supply of oxygen is less than 

 in ordinary putrefaction, which may be understood thus : — 



12 6 18 24 = Carbonic Acid and Ammonia 



which escape, and the attraction of which for each other, no doubt in part deter- 

 mines the result. 



2. Again, in the living body, but in a feeble constitution, along with great 

 emaciation, and a deficient supply of oxygen, a morbid deposition of fat some- 

 times takes place, in circumstances where it could not have been anticipated, but 

 only in particular parts. Some distinct cases of this kind have lately attracted 

 attention, one in the kidneys, in one form of Bright's disease, another in the 

 liver, as in many phthisical cases, and a third in the atheromatous exudations 



VOL. XVI. PAET III. 4 I 



