420 
LIEBIG REVIEWED. 
The process of nutrition in the graminivorous animals appears at 
first sight altogether different. Their digestive organs are more 
complicated, and their food consists of vegetables, the great mass of 
which contains but little nitrogen. We have already seen that 
vegetables produce, in their organism, the blood of all animals ; for 
the carnivora, in consuming the blood and flesh of the graminivora, 
consume, strictly speaking, only the vegetable principles which 
have served for the nutrition of the latter. Thus vegetable fibrine 
and albumen take the same form in the stomachs of graminivorous 
animals, as animal fibrine and albumen do in that of the carnivora. 
These few facts will give to the student a tolerably clear con- 
ception whence the increase of mass in an animal is derived. But 
another more difficult task remains, viz. to shew the manner in 
which this is accomplished in the living organism. 
We have seen that the organic part of the food contains carbon, 
hydrogen, oxygen, and nitrogen, the elements of which the organic 
parts of the body are composed ; the inorganic portion also, which 
exists in the food, contains the lime, the magnesia, the potash, the 
soda, the sulphur, the phosphorus, and the iron, which exists in 
the organic parts of the animal body. The body obtains from the 
food all the elements of which it consists ; and if these be not pre- 
sent in the food, the body of the animal cannot be properly built 
up and supported. But now comes the most interesting part of 
the question, as to the state in which these elements enter into 
the body. 
We have seen that the plant is the compounder of the raw ma- 
terials and living bodies, which it derives from the air, the earth, 
and the waters. The herbivorous animal uses up these raw mate- 
rials, cutting them into shape when necessary, and fitting them to 
the several places into which they are intended to be built; but 
these different substances require to be all resolved into their ori- 
ginal elements before they can become a part or portion of the liv- 
ing organism, and are then built up, as it were, by the vital powers 
according to their peculiar organization and the various structures. 
There is a great difference in the various articles of food, as far 
as their capability of affording the necessary quantity of building 
materials is concerned; some possessing the plastic materials in an 
eminent degree, while others possess an exceedingly small per 
centage of them, varying from 1 to 25 per cent. The following 
table, which is the result of Dr. Playfair and Brassingault’s 
analysis, will illustrate this. The azotized column indicates the 
flesh-forming principle, whilst the unazotized column has refer- 
ence only to the quantity of fatty matters contained in the various 
articles of diet : these vary from 8 to 68 per cent. : — 
