52 PRINCIPLES OF ANIMAL NUTRITION. 
bolism, they mean that from 100 grams of proteids there is pro- 
duced, according to the first scheme, 27.61 grams of ‘fat, and that 
from this, by the addition of oxygen, 44.67 grams of sugar are 
formed. Some of the evidence by which these equations are sup- 
ported will be considered in another connection, but may be antici- 
pated here in the statement that, in the judgment of the writer, it 
is far from sufficient to establish them as quantitative statements. 
THE NON-PROTEIDS. 
Under this comprehensive but somewhat vague term have been 
grouped all those numerous nitrogenous constituents of the food 
which are not proteid in their nature, the name being a contraction 
of non-proteid nitrogenous substances. It includes the extractives 
of meat, and in vegetable foods several groups of substances, of 
which, however, the amides and amido-acids are most abundant. 
Various substances of this class are produced by the splitting up of 
the reserve proteids in the germination of seeds and apparently 
also to some extent in the translocation of proteids in the growing 
plant, while some at least of them appear to be produced syntheti- 
cally from inorganic materials and to be the forerunners of pro- 
teids. In young plants a considerable proportion of the so-called 
crude protein (N X 6.25) often consists of these non-proteids, and 
considerable interest, therefore, attaches to their transformations 
in the body. 
AMIDES OXIDIZED IN THE Bopy.—It has been shown by numer- 
ous investigators that various amides and amido-acids when added 
to the food are oxidized, giving rise to a production of urea. 
Shultzen & Nencki* found that glycocol, leucin, and tyrosin were 
thus oxidized, while acetamid apparently was not. So far as 
glycocol is concerned, this result is what would have been expected, 
since, as we have seen (p. 44), this body appears to be normally 
formed in the body as an intermediate product of proteid meta- 
bolism. Similar results were obtained by v. Knieriem + from 
trials with asparagin, aspartic acid, glycocol, and leucin. Munk t 
likewise found that the ingestion of asparagin increased the pro- 
* Zeit. f. Biol. 8, 124. 
+ Ibid., 10,277; , 36. 
$ Virchow’s Archiv. f. path. Anat., 94, 441, 
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