36 MILK AND ITS HYGIENIC RELATIONS 



The large amount of caseinogen present in cows' milk as com- 

 pared with human milk, has, until the last few years, formed a 

 prominent feature of the voluminous literature upon infant-feeding. 

 It is probable that this has been the determining factor in the 

 question of the dilution of cows' milk for infants, since average 

 cows' milk contains less sugar and fat than human milk. 



Any general discussion upon the digestibility of cows' caseinogen 

 for infants would be beyond the scope of the present work, but a 

 few points may be considered. 



The numerous papers published both in America and Germany 

 in recent years show no reason to suppose that the infant cannot 

 digest cows' caseinogen. The so-called 'casein' curd of infants' 

 stools has been shown not to be due to casein, but to the salts of 

 fatty acids. 



Finkelstein reviewed the factors which at various times have 

 been regarded as the detrimental element in artificial feeding. He 

 says : ' Improved clinical observations, the metabolism experiments, 

 and the comparative researches upon the fat of cows' and human 

 caseinogen in the infant's intestine have concordantly demon- 

 strated that the disturbance must have its origin in other circum- 

 stances than in the harmful casein residue ' (schddliche Kaseinrest). 



In this country little research work has been carried out upon 

 this matter. Cameron, however, reviewing the whole question, 

 says, ' The disturbances of protein digestion are, generally speaking, 

 secondary to fermentative dyspepsia. Although all that we know 

 of the chemistry of infantile digestion and much accurate clinical 

 observation point to this conclusion, it is often authoritatively 

 taught that the protein of cows' milk is the most frequent source 

 of trouble, and that which most commonly causes vomiting and 

 colic,' and ' Evidence that diarrhoea and colic are caused by abnor- 

 mal protein digestion is not forthcoming. In the stools of an infant 

 fed upon cows' milk there are always present, in more or less 

 abundance, white curd-like masses of soaps, formed by the com- 

 bination of the fatty acids derived from the food with calcium 

 and magnesium. These whitish curd-like masses of soap have 

 much the appearance of undigested casein curds of milk, and their 

 presence accounts for the frequent description of the stools by 

 mothers and nurses as "undigested."' Bauer (6) finds that true 

 casein curds do sometimes occur in infants' stools, but he says that 

 they occur only when the children are fed on raw cow's milk, dis- 

 appearing when the milk given has been heated. This is also 

 stated by Brennemann. 



From the hygienic standpoint it would not appear necessary 

 to deal any further with the differences in the protein content of 

 human and cows' milk. In colostrum the whole question assumes 

 an important biological aspect, which will be considered below. 



The Chemical Composition of Caseinogen and Lact-albumin. 

 Several investigations into the chemical composition both of 



