74 MILK AND ITS HYGIENIC RELATIONS 



of lactation. No nutritional value has been attributed to it by any 

 observer. 



Two other ferments have been the subject of considerable in- 

 vestigations which do not belong either to the ferments acting upon 

 substances present in milk, nor have they been used for commercial 

 or public purposes. These ferments are amylase, which acts upon 

 starch, converting it into dextrin, and salolase, which acts upon salol, 

 converting it into phenol, and salicylic acid. It is difficult to 

 imagine that either of these substances can play any part in the 

 nutrition of the infant. 



Amylase. There is no starch in milk, but amylase is present 

 in considerable quantities in the blood, and it is most probable 

 that it is present in milk as a result of filtration. 



Another source of this ferment may be the mammary gland, since 

 Grimmer obtained evidence of its presence in his experiments on 

 gland tissue, even in those animals where little or no amylase 

 was found in the milk. 



A considerable number of observers have investigated the 

 presence in both cows' milk and human milk of a ferment capable 

 of splitting starch into simpler bodies. 



Amylase in Human Milk. Human milk appears to possess 

 the capacity of splitting starch, all observers being agreed upon this 

 point. The amount of starch which can be converted within a 

 period of a few hours is not large, although the action is quite 

 definite. It has long been known that amylase is present in 

 the blood, and it is probable that the presence of this ferment in 

 milk is due to filtration through from the blood itself. 



Amylase in Cows 9 Milk. There is some difference of opinion 

 among investigators in regard to the presence of amylase in cows' 

 milk. A number of observers have entirely failed to find any 

 evidence of this ferment in the milk of this animal. When found, 

 it is present only in small quantities. Thus Giffhorn, in 1910, 

 found that 100 gms. of milk will decompose from *oi to '25 gm. of 

 starch. In experiments carried out by myself upon cows' milk, 

 it appeared that 10 c.c. of cows' milk were capable of splitting from 

 ooi to -002 gm. of starch in three hours in an incubator kept at 

 a temperature of 37 C. Evidently, therefore, the strength of this 

 ferment in cows' milk is so small as to be insignificant, and, more- 

 over, the digestive juices are much richer in amylase than is milk. 



Salolase. This substance has not so far been found in cows' 

 milk, but it has been almost universally found in human milk 

 by those who have investigated its presence. There is some doubt 

 as to its true nature, since certain observers have stated that the 

 reaction is still present after the milk has been boiled, which would 

 not be the case were the reaction produced by an enzyme. It is 

 difficult to postulate any value for this property of human milk 

 in the nutrition of the infant, since salol is not present in milk 

 nor in the infant's stomach. If it is not due to a ferment, it must 



