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 hardly more vital than the formation of adipocere,—in 
both 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. 
3. 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 formation 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 ; ¢. g., the changes in the vinous fermentation 
of grape-sugar, are represented thus,— 
Cy H,, Oy =2-(C, H, 0,) +4 CO, 4+ 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 
new 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 third 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 same course as those portions 
which are resolved into carbonic acid and water. In the one case, the com- 
pound formed, C, H, 02, contains a less proportion of carbon than any of those 
which we regard as endowed with strictly vital properties; while, in the other, 
the compound formed, C,, Hi O,, has the characteristic predominance of carbon. 
3ut 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 be, 

