56 
MISCELLANEA. 
clearly be the most suitable which in the same weight contains the 
greatest quantity of these substances. The exact appreciation of 
the azotized substances, such as gluten and albumen, is not without 
difficulty; it requires much time and care. But if it. is once ad- 
mitted that the nutritive value of food increases in proportion as 
they increase, it is clear that this amounts to the same thing, with 
the value being proportional to the quantity of azote it contains. 
The quantity of azote is easily ascertained, whereas the apprecia- 
tion of the albumen and gluten requires much tedious manipulation. 
The proportion of azote being once known, it is easy to calculate 
the amount of albumen (or flesh) contained in any given food; for, 
in general, vegetable nutriment does not contain any other azotized 
principle. It is true, all azotized vegetable principles cannot be 
considered as nutritious. Some are violent poisons, or active medi- 
cines ; but these poisonous matters are not met with in any appre- 
ciable quantity in such plants as are used for nutriment; and, 
indeed, when once any particular plant is admitted as an article of 
food for animals, we may assume the absence of any injurious prin- 
ciple. All vegetable substances which are used for the food of 
herbivorous animals, as far as they have been at present examined, 
contain, in point of fact, a certain quantity of azotized constituents. 
We know from the researches of Dr. Magendie, that food void of 
azote will not support life. Animals subjected to such a regimen 
lose their condition, and at last die. On the other hand, we know 
that the value of any kind of flour increases with the gluten it con- 
tains. It is because the seeds of leguminous plants, such as kid- 
ney-beans, peas, beans, &c., are richer in azotized principles (that 
is in flesh) than corn, that they are also more nutritious. 
From all these considerations, I have admitted that the nutritive 
quality of vegetables depends mainly on their azotized constitu- 
ents, and that in consequence their nutritive quality is proportional 
to the quantity of azote which they contain. It must, however, be 
remarked that I am far from thinking that azotized substances are 
sufficient for nutriment, but it is matter of fact that any vegetable 
nutriment highly azotized is, in general, accompanied by the other 
organic and inorganic principles which concur in the act of nutri- 
tion. In estimating the azote of many kinds of food, I have tried 
to find a base to serve as a fixed point for appreciating compara- 
tively their nutritious qualities. The agriculturists of Germany 
and England have long tried to solve this important problem of 
rural economy. It is with this view that Thaer and others have 
given, as the result of their researches, numbers to express in weight 
the proportion in which one kind of food may be substituted for 
another : they indicate, for example, that a given quantity of hay 
or roots may be replaced by another of leaves or grains to nourish 
