The Mortality of Infants. 87 



that these differences may be the cause of grave de- 

 rangements, and this, in fact, is the case. 



The principal difference, and the one which before 

 all others claims correction, is the excess of casein in 

 cow's milk in a form not of easy digestion ; further- 

 more, the scantness of milk sugar and of albumen. 



Medical authorities do not seem to entirely agree 

 on the eqirality of the chemical composition of the 

 casein in cow's milk and in human milk ; we may, 

 however, without attempting to express an opinion 

 on this matter, fix our attention on the difference in 

 digestability of the two caseins, as this is of prime 

 importance in the process of the infant's nourishment. 

 If a small quantity of woman's milk be taken and a 

 few drops of extract of rennet added, in imitation of 

 the process inacted in the infant's stomach, it will be 

 seen that this milk coagulates in the form of finest 

 flakes, looking more like very minute grits, while, if 

 we repeat this experiment with cow's milk, we shall 

 see the casein formed into large, more or less com- 

 pact, lumps. The digesting juices of the infant's 

 stomach are able easily to reduce the finely curdled 

 casein of mother's milk, but the lumps of the cow 

 casein are not easily digested, cause inconvenience, 

 and are as we all have had occasion to observe, fre- 

 quently ejected from the infant's stomach. To reduce 

 the amount of casein in cow's milk by diluting with 

 water is a proceeding adopted by many ; it is not, 

 however, a recipe to bring the milk any closer in 

 composition to mother's milk, as, by so doing, we re- 



