719 
efforts of the organism to get rid of the fat in this way as to the 
natural tendency of fat to undergo this action when exposed to the 
action of alkaline fluids such as the intestinal secretions. In this 
way an excessive abstraction of the alkaline bases of the body takes 
place, which are in turn supplied to the body, in milk at least, in 
quantities merely sufficient for a normal diet. The income, then, of 
these bases becomes less than the outgo, and a pathological condition 
due to this diminution is thereby induced. Owing to the greater 
energy required in its digestion, the tendency of cow’s milk is to 
remain longer in the intestinal tract. This gives greater opportu- 
nity for any excess of fat present to rob the body of alkaline bases by 
virtue of its saponification. As a consequence of the general richness 
of cow’s milk in this country, such danger of excess of fat must 
always be present when the milk used as an article of infant food 
is not controlled in this respect. It would seem that a milk which 
contains 4 per cent of butter fat were somewhat too rich and that a 
fat content of 3 to 3.5 per cent would be nearer the mark to insure 
success in infant feeding. The experience of dairymen tells us that 
calves do best on this ; moreover, the production of rich milk in cows 
is not attended by a corresponding increase in the salts present, as 
rich milk is a result of careful breeding for that purpose by man, and 
is not a condition original to the milk of the cow. 
The second effect excessive fat has in promoting gastro-intestinal 
disturbances lies in its behavior when casein is curded by rennet in the 
stomach. It is well known, among cheese makers at least, that casein, 
when coagulated by rennet, carries down with it a very large per 
cent of the butter fat present. This is well shown in the case of the 
cream cheeses, some of which contain nearly six times as much fat in 
their composition as casein. As the whey from whole milk contains 
no casein and less than 1 per cent of fat, it is obvious that the casein 
when curded brought down with it some 75 per cent or more, accord- 
ing to the richness of the milk, of all the butter fat originally present 
in the milk. The practical bearing this has upon the digestibility of 
cow’s milk proteid is as follows: The richer the milk in fat, the 
greater percentage of fat will then be in the curd formed by the 
gastric digestion. 
A very simple experiment will show in what way the digestibility 
of a rich whole milk would thereby be affected. Place a small por- 
tion of skimmed milk in a small flask with a narrow neck. In an- 
other flask place a similar portion of a rich milk containing say 5 
or 5.25 per cent of fat. Add a small portion of liquid rennet to each, 
cork, and turn them slowly over and over in order to simulate peri- 
staltic action. In the case of the skimmed milk, as curding takes 
place, we see the formation of a flocculent curd, each particle of 
which remains separate. In the case of the milk rich in fat, the curds 
