56 PRINCIPLES OF ANIMAL NUTRITION. 
‘ie nutritive ratio of 1:7.7, and caused neither a gain nor 
a loss a consequence. 
Particular interest attaches to Kellner’s second experiment in 
which ammonium acetate was added to a ration poor in protein 
(1:19), followed in a third period by a quantity of asparagin con- 
taining the same amount of nitrogen. The average amounts of 
protein (N X 6.25) gained per day and head by the two lambs 
were as follows: 
Basal ration .......... 0.0.00 seen eee es 4.12 grms. 
et ‘« + ammonium acetate...... 15.56 “ 
«+ asparagin.......... 0.06 15.69 “ 
Although it is impossible to suppose that the ammonium acetate 
is capable of performing any of the functions of proteids in the 
body, it nevertheless caused as great a gain of protein by the body 
as did the asparagin. The only obvious explanation is that both 
these substances acted in the manner suggested by Zuntz to protect 
the small amount of protein in the food from the attacks of the 
organized ferments of the digestive tract. Accepting this explana- ~ 
tion, we must suppose that when the contents of the alimentary 
canal contain a normal amount of proteids the micro-organisms 
find an abundant supply of nitrogenous food in their cleavage 
products and reach their normal development, so that an addition 
of soluble nitrogenous substances is a matter of indifference. When, 
on the other hand, the amount of protein present is abnormally 
low, as in Weiske’s and Kellner’s experiments, the organisms are 
limited in their food-supply and attack the food proteids them- 
selves. 
Kellner’s results stand in apparent contradiction to the earlier 
ones of Weiske and Flechsig,* who report no gain of proteids as re- 
sulting from the addition on three days of a mixture of ammonium 
carbonate and acetate to a ration poor in protein. The excretion 
of sulphur in the urine was likewise unaffected. They assume, 
however, a long-continued after effect of the ammonium salts on the 
nitrogen excretion. If the comparison be limited to the three days 
on which the ammonium salts were given and the next following 
day, a gain of 1.15 grams of nitrogen per day results, but, as just 
stated, there was no corresponding gain of sulphur. 
*Journ. f. Landw., 88, 137. 
