New. YorK AGRICULTURAL EXPERIMENT STATION, 207 
the peptones, thus cutting out a part of the amido-acid com- 
pounds and counting that part among the peptones? Or is 
there in the cheese only the small amount of end-products in- 
dicated by the action of the phosphotungstic acid? 
While we did not by individual isolation determine to what 
extent amido compounds were present, we are justified in be- 
lieving that such compounds were not yet present in the cheese 
in any appreciable degree; and, hence, the figures obtained 
with phosphotungstic acid are much nearer the truth than those 
obtained by tannin-salt precipitation. We will state our rea- 
sons for this belief. The amido compounds precipitated by phos- 
photungstic acid are known to be chiefly the diamido com- 
pounds, while the monoamido compounds are precipitated little, 
if at all. Hence, the compounds found in the filtrate of a phos- 
photungstic acid precipitation are mainly monoamido com- 
pounds. Now let us assume temporarily that the amounts of 
nitrogen in the tannin-salt filtrate, given in the table above, 
represent the total amido compounds, free from peptones; 
then, since the monoamido compounds are represented by the 
amounts of nitrogen obtained in the phosphotungstic acid fil- 
trate, the difference between the two sets of figures, that is, 
those obtained by tannin-salt solution and those obtained by 
phosphotungstic acid, represents the amount of diamido com- 
pounds, Taking the average of the results given in the table 
above, the nitrogen of the total amido compounds is 0.574 per 
ct. of the cheese, while the nitrogen of the monoamido com- 
pounds is 0.128 per ct. of the cheese, thus leaving the difference 
as the nitrogen of the diamido compounds equivalent to 0.446 
per ct. of the cheese. According to these figures, the mono- 
amido compounds constitute about 22 per ct. of the entire 
amount of amido bodies, while the remainder, 78 per ct., repre- 
sents largely diamido compounds. In this case, the ratio of 
monoamido to diamido compounds is as 1 to 3.5. Keeping these 
data in mind, we will call attention to some work done by 
Hart!® in studying the cleavage end-products formed by the 
action of hydrochloric acid on casein. He found that the 
diamido compounds formed less than 20 per ct. of the total 

16Zeit. f. Physiol. Chem., 33: 247 (1901). 
