lunt *$,'*<>17 
Methods of Estimation of Metabolic Nitrogen 
411 
a pronounced dislike for the blood albumen. The acid-pepsin method 
indicates that this pig was less able than others to digest this foodstuff. 
Also, we would observe that, in response to most insistent demands for 
food, we gave to pig 5 in Period II a larger allowance of food per unit 
of body weight than was given to the other individuals. The digestion 
coefficient for blood albumen, as determined by the acid-pepsin method, 
with this pig also is low. Further, these two pigs, No. 1 and 5, had the 
lowest digestion coefficients, as determined by the acid-pepsin method, 
in the following period, No. Ill, where skim milk was fed. 
In a study of the effects on metabolic nitrogen of storage of the 
feces in a frozen condition for 20 days, with and without the addition of 
thymol, compared with air-drying the fresh material, with and without 
thymol, no significant differences were observed which could be related 
to these methods of preservation. 
In attempting to choose between these methods it seems to us that the 
add-pepsin and the pepsin-pancreatin methods give results which are 
more nearly true than does Jordan's method, since the latter does not 
digest the bacteria, which may contain large proportions of the nitrogen 
of the feces and which presumably are more largely the product of 
digestible than of indigestible protein; but it is idle to attempt close 
comparisons of such conventional and inaccurate procedures. We have 
no accurate sdentific basis for the determination of the digestibility of 
protein. 
