BREASTS AND MILK. 383 



of the nurse of a syphilitic child is, therefore, a very con- 

 venient treatment. 1 



Milk forms the type of a perfect aliment (see p. 209), being, 

 for a considerable time, the only food of the child ; the case 

 is the same with regard to the egg, which forms a similar 

 aliment for the bird. All the elements necessary to nutrition 

 have been found, by analysis, to exist in milk (see Sbove) as 

 well as in the egg: salts, hydrocarbons, and albuminoids. 

 The proportions of these various substances in milk are not, 

 however, exactly the same as have been generally supposed 

 necessary to a properly mixed diet. It is generally admitted 

 (Moleschott, Voit) that an adult consumes 320 grms. of car- 

 bon and 21 grms. of nitrogen, or, in other words, 130 grms. 

 of albuminoid elements, and 488 grms. of hydrocarbons and 

 fats (tats 84, hydrocarbons 404) ; it follows that, in this case, 

 the normal proportion, in a mixed diet, of nitrogenous to 

 non-nitrogenous aliments, is 1 to 3.7, while in milk, as well 

 as in the egg, the proportion is 1 to 3, or, even, 1 to 2 : in 

 other words, the quantity of albuminates (nitrogen) is much 

 larger, and of hydrocarbons (carbon) much smaller. This 

 fact may be easily explained, by referring to what we have 

 already said (p. 78), as to the importance of the hydrocarbons, 

 in regard to the production of force, muscular force espe- 

 cially: the adult draws his forces from the combustion of non- 

 nitrogenous substances, the albuminates scarcely serving for 

 this purpose. On the other hand, when the organism is in 

 course of development, the nitrogenous substances are indis- 

 pensable to the growth of the different tissues. It is, there- 

 fore, easy to see how mistaken is the common practice of 

 condemning children to a diet containing a large quantity of 

 starch, and scarcely any nitrogen. 2 The differences in com- 

 position of the milk of the different mammals (see above), 

 are probably connected with the greater or smaller quantity 

 of living force which the young animals possess at birth : 

 thus young calves and colts walk and run almost imme- 

 diately; therefore, they must, at the very first, produce a 

 considerable amount of force, and we have seen that the rnilk 

 of the cow and the marc contain a large proportion of hydro- 

 carbons (fat in the cow, and sugar in the mare and the ass). 

 Similar differences are also observed in the eggs of different 

 birds. 



1 See " Journal de 1'Anat.," de Ch. Robin. Janvier, 1873. 



2 Wundt, " Physiologic." Trad, de A. Bouchard. 



