54 PRINCIPLES OF ANIMAL NUTRITION. 
The earliest investigations upon this point are those of Weiske * 
and his associates upon the nutritive value of asparagin. The 
experiments were made upon rabbits, hens, geese, sheep, and goats, 
and in the case of the two latter species included experiments on 
milk production. While the experiments are open to criticism in 
some respects, as a whole they seemed to show that asparagin, 
especially when added to a ration poor in proteids, caused a gain of 
proteids by the body. Weiske accordingly concluded that aspara- 
gin, while not capable of conversion into proteids, was capable of 
partially performing their functions and thus acting indirectly as a 
source of proteids, and this view has been somewhat generally 
accepted. Subsequent experiments by Bahlmann,t Schrodt,{ 
Potthast,§ Meyer,|| and Chomsky § upon milch-cows, rabbits, and 
sheep gave results which tended to confirm Weiske’s conclusions. 
Not all of Weiske’s experiments, however, gave positive results 
in favor of asparagin, and experiments upon carnivorous and omniv- 
orous animals have failed to show any such effect. In addition 
to the experiments of Politis and of Gabriel, referred to above, 
Mauthner,** Munk,{t+ and Hagemann {f have failed to observe any 
gain of proteids by the body as a result of the ingestion of asparagin, 
but found simply an increase in the apparent proteid metabolism 
as measured by the urinary nitrogen. 
Influence on Digestion—It can hardly be assumed that the 
actual processes of metabolism in the body tissues are fundamen- 
tally different in different species of mammals, and investigators 
have therefore been led to seek an explanation of the striking differ- 
ence in the effects of asparagin on herbivora and carnivora in the 
differences in the digestive processes of the two classes of animals. 
Digestion in herbivora is a relatively slow process and, as pointed 
out in Chapter I, is accompanied by extensive fermentations par- 
* Zeit. f. Biol., 15, 261° 17, 415; 30, 254. 
+ Reported by Zuntz, Arch. f. (Anat. u.) Physiol., 1882, 424, 
tJahresb, Agr. Chem., 26, 426. 
§ Arch. ges. Physiol., 32, 288. 
|| Cf. Kellner, Zeit. f. Biol., 39, 324. 
{| Ber. physiol. Lab. Landw. Inst. Halle, 1898, Heft 13, p- 1. 
** Zeit. f. Biol., 28, 507. 
tt Virchow’s Arch. f. path. Anat., 94, 441. 
t{Landw. Jahrb., 20, 264. 
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