659 
catecl. Thus various alkalies and diluents have been applied, the 
percentage of proteids has by modification been attenuated almost to 
the vanishing point, split proteids have been advocated, a portion of 
the casein being replaced by whey proteid — in short, almost every 
conceivable device that ingenuity could suggest. 
This would be highly commendable were cow’s milk proteid really 
so difficult of digestion by the human infant. The researches of the 
investigators just adverted to have shown this important fact, viz, 
that cow’s milk proteid is almost as easily digestible per se by infants 
as are the proteids of woman’s milk. In this country Brennemann and 
Walls a have confirmed this view. On the other hand, Czerny and 
Keller have shown that the element in cow’s milk which causes di- 
gestive disturbance is the fat and not the proteid. They have given 
us a very precise and definite clinical picture of these disturbances, a 
picture perfectly familiar to all who have dealt much with the arti- 
ficial feeding of infants, but which has been ascribed heretofore in 
this country to difficult proteid digestion. 
Let us then examine the basis for this belief which has hitherto 
been regarded as a fundamental fact ever to be considered in the 
percentage system of the modification of cow’s milk. It has been 
based for the most part on these facts: First, that in the stools fol- 
lowing gastro-intestinal disturbances in infants a large number of 
apparent curds are mingled with the fecal discharge. They look like 
curds arid have been taken for curds without further investiga- 
tion. Czerny has shown that they consist for the most part of saponi- 
fied fat, neutral fat, and fatty acids, interspersed in severe cases with 
clumps of bacteria. 
If infants are fed on fat-free cow’s milk, although the milk be un- 
diluted and containing 3.50 per cent of bovine proteid, no trace of 
casein appears microscopically in the stools, yet Chapin tells us it is 
rare to find an infant 10 months of age who will digest more than 
1.50 to 2 per cent of cow’s milk proteid. 
In this country, the digestibility of cow’s milk proteid has been 
confirmed by Walls * * 6 after a series of hundreds of observations. Xow 
Czerny has shown that the persistent ingestion in a child of a diet 
with an energy quotient surpassing 100 calories per kilogram of body 
weight is invariably followed sooner or later by nutritional disturb- 
ances. Owing to the fact that infants receive for the most part 
nothing but milk, and that the percentage of sugar and proteid in 
milk is pretty nearly constant, it follows by reason of the high caloric 
value of the fat (9.3 calories) that a high energy quotient implies an 
excess of fat. It is impossible, by mere inadvertence, with carbohv- 
a Am. Journal Med. Ass., 1907, Yol. XLYIII, 1338-1344; Ibid, F. X. Walls, 
pp. 1389 to 1392. 
6 F. X. Walls, Am. Jour. Med. Sei., 1906, II, 
