EoBERTON. — Milk as a Vehicle of Disease. 571 



food ; but closely allied to this subject, and I believe of even 

 greater importance, is that which more especially concerns us 

 to-night — " The extent to which milk may serve as a vehicle 

 of disease." 



The importance of the matter cannot be understood unless 

 we have a fair idea of the part which milk plays as an article 

 of human food, and it may be well for us to turn our attention 

 to this for a few minutes. 



Milk has been called by an author famous as an authority 

 on the subject of diet a complete and perfect food. It con- 

 tains all those elements w-hicli are constituents of a sufficient 

 and healthy food for man. These elements are — (1) Sub- 

 stances containing nitrogen ; (2) carbohydrates, a name given 

 to a class of chemical bodies in which are the starches and 

 sugars ; (3) fats ; (tt) mineral salts. 



Children and adults usually take what is called a mixed 

 diet, some parts of their food (such as meat) containing mostly 

 nitrogenous matter ; potatoes are chiefly starch ; butter is 

 nearly all fat. Their different foods are taken in no fixed pro- 

 portions, but as taste or opportunity may direct — more of one 

 and less of another. Although, however, one may put into 

 one's mouth very indefinite quantities of each element of food, 

 one's digestive apparatus has only limited capabilities for the 

 digestion of each of them, and only a limited amount of the 

 whole food is really digested. The remainder simply goes to 

 waste, and is eliminated. 



The stomachs of all individuals are not equally strong^/. c, 

 they have not equal powers of digestion — and in the extremes 

 of life (both in infancy and in old age) the digestive powers 

 are cop^paratively weak. The same Providence which endues 

 an infant with a weak stomach provides for it in milk a food 

 in which the fats, the matter containing nitrogen, the sugar, 

 and the salts are mixed in the quantities and form best for 

 their easy digestion. 



All milks are not exactly alike as to the proportion of their 

 various ingredients. What will suit a foal is not the best for 

 a lamb, nor, as a rule, is the milk of a cow so good for a human 

 infant as that from its own mother's breast. Still, in cases 

 where a mother may not or will not nurse her own offspring, 

 and a good wet-nurse is not procurable, the best substitute 

 for the child's natural food is undoubtedly milk from some 

 other animal. Among most European nations the cow is the 

 chosen animal, but the goat, ewe, mare, and reindeer are used 

 in some districts. 



Not only, however, to infants is it an advantage to have a 

 good supply of milk — as we have seen, a complete food in a 

 form easy for digestion ; for the old and the invalid it is at times 

 invaluable, and for the rest of mankind, especially for the 



