310 DR ALISON'S OBSERVATIONS ON 



SO common on the arteries. It may be suspected that in these cases the forma- 

 tion of fat is by an affinity haixUy more vital than tlie formation of adipocere, — in 

 botli cases the decomposition of albumen to form the fat, being aided by the 

 simply chemical affinities, of carbon for oxygen, and of hydrogen for azote. 



•']. The same peculiarity of the attractions by which fat is formed in the animal 

 economy may be admitted in explanation of the more general fact, that in a 

 healthy constitution, when more, particularly of amylaceous, food is taken than 

 is required for the nutrition of the more important textures, and when little oxy- 

 gen is taken in, the excess always tends to the deposition of fat, which implies 

 that a large portion of the oxygen of that food has gone ofF as carbonic acid and 

 water. 



The process of the formation of oil from starch in the animal body, admits of 

 an instructive comparison with the simply chemical one of the fonnation of alco- 

 hol from the same matter, — at least, from a compound fluid of which starch (first 

 converted into sugar by the kind of fermentation formerly mentioned) is the 

 chief constituent, in fermentation ; e. y., the changes in the vinous fennentatioii 

 of grape-sugar, are represented thus, — 



C,, Hj, 0,^ = 2 (C, He 0,,) + 4 CO, + 2 HO, 



that is, the elements of grape-sugar resolve themselves into two equivalents of al- 

 cohol, four of carbonic acid, and two of water. In this case, as in the formation of 

 fat, the starch or sugar is divided into three parts, water, carbonic acid, and a pecu- 

 liar compound fluid. In both cases, the oxygen of the air is necessary to the com- 

 mencement, and probably to the continuance, of the process, although in both, the 

 neM' compound formed contains less oxygen than the starch or sugar from which it 

 is produced. In both cases, a third body is present, and its influence somehow pro- 

 motes the process, besides the oxygen and the starch, viz., in the one case, yeast, 

 or some kind of ferment, itself in a state of decomposition, which it imparts, without 

 giving up any part of its substance, to the starch or sugar ; in the other case, a living 

 cell, composed of gelatin, which is itself undergoing a simultaneous change, by a 

 living process. In both cases, extension of the change takes place, as from a centre, 

 from this thu-d body, through the fluid in which the change commences. In both 

 cases, the compound formed is not stable ; and the portions of the starch which 

 go to form it are destined ultimately to follow the stime ('(jurse as those portions 

 which are resolved hito carlioniu acid and water. In the one ease, the ((jm- 

 pound formed, C^ H,; O^, contains a less proportion of carbon than any of those 

 which we regard as endowed vntXx strictly vital properties ; while, in the other, 

 the compound formed, Ci- Hi,, Oi, has the characteristic predominance of carbon. 

 r>ut if we are asked. Why we regard the one as the result of a simply chemical 

 process, and the other of a vital affinity ? I apprehend the sufficient answer to l)e. 



