496 
DR. PROUT ON ANIMAL CHEMISTRY. 
of digestion, which may be conveniently considered under the 
three following heads:—first, of the essential changes which the 
alimentary substances undergo ; secondly, of the nature of the 
merorganization of the alimentary substances; and, thirdly, of 
the reduction of the alimentary substances or their combination 
with water, and consequent solution in that flood; all of which 
constitute so many distinct functions, each liable to its peculiar 
derangements and mode of treatment. 
1. With respect to the essential changes which the alimentary 
matters undergo, it may be remarked that two of them, the 
oleaginous and albuminous, are animal products, or parts of other 
animals, appropriated as articles of food, and hence may be sup¬ 
posed capable of being at once applied to the purposes of the 
animal economy without undergoing any essential change in their 
composition. But with the saccharine class, derived principally 
from the vegetable kingdom, the case is different; and before this 
can be converted, either into the oleaginous or the albuminous 
principles, it must undergo some essential change or changes in 
its composition. These essential changes, I believe, are purely 
chemical, and the results of obvious and common affinities, and 
will, I have no doubt, be known hereafter; but as I have not yet 
quite made up my mind on some points connected with the albu¬ 
minous principle, I shall not enter further on the subject at pre¬ 
sent. I may remark, however, that whatever be the nature of 
the food, the general composition of the chyle is the same, though 
the proportions of the ingredients are liable to very considerable 
variations, according to the nature of the food: thus, if consi¬ 
derable quantities of fat be taken, the chyle will be found to 
abound in fat, &c. 
2. Of the nature of the merorganizing Processes .—In this part 
of the inquiry lie the real difficulties we have to contend with, in 
the operations of life. All the great and essential changes can be 
traced by care and attention, but here we meet with much which 
will probably for ever remain unknown to us; and even the little 
that we do know can scarcely be satisfactorily applied at present. 
The merorganizing processes may be considered as constituting a 
sort of underplot, carried on by the organic agent, by which it 
contrives to influence and direct the operations of the material 
principles of wdiich living bodies are composed; and though 
we can see and understand the nature of these principles, 
and even follow them through many of their metamorphoses, 
yet we cannot detect the nature of the concealed agencies that 
govern the whole, or perhaps, at the utmost, catch a glimpse 
only of a half-concealed clue, the uses and connexions of which 
are unknown to us, and serve only to puzzle us the more. From 
