298 SECRETION 



COMPOSITION OF HUMAN MILK 



Water 902.717 to 863.149 



Casein (desiccated) . 29.000 to 39.000 



Lactoprotein *." i.ooo to 2.770 



Lactalbumin and lactoglobulin . . . V ". traces to 0.880 



f Palmitin . . . . 17.000 to 25.840 



Butter, 25 to 38 j Olein . . . . . . . 7.500 to 11.400 



I Butyrin, caprin, capro'in, caprylin etc. 0.500 to 0.760 



Sugar of milk (lactose) . . . . , . 37.060 to 49.000 



Sodium lactate (?) . . . ... . 0.420 to 0.450 



Sodium chloride . . . . JA . . . 0.240 to 0.340 



Potassium chloride . i . . ' . . -. 1.440 to 1-830 



Sodium carbonate - % - . . . v , . . 0.053 to 0.056 



Calcium carbonate . ' , . ~ ."'-- 0.069 t 0.070 



Calcium phosphate *. . ..... . . 2.310 to 3.440 



Magnesium phosphate .' . , . . . 0.420 to 0.640 



Sodium phosphate 0.225 to 0.230 



Ferric phosphate (?) .... . . . 0.032 to 0.070 



Sodium sulphate . . . ... . . 0.074 to 0.075 



Potassium sulphate . . . , , . . . traces. 



1000.000 1000.000 

 f Oxygen 1.29) 



Gases in solution j Nitrogen 12. 17 ^30 parts per 1000 in volume. 



I Carbon dioxide 16.54 j 



The proportion of water in milk is subject to certain changes, but 

 these are not so considerable as might be expected from the great 

 variations in the entire quantity of the secretion. As regards the 

 quantity of milk in the twenty-four hours, the influence of drinks, even 

 when nothing but pure water is taken, is very marked ; and although 

 the activity of the secretion is much increased by fluid ingesta, the 

 quality of the milk usually is not affected, and the proportion of water 

 to the solid matters remains about the same. 



Nitrogenous Constituents of Milk. Little remains to be said con- 

 cerning the nitrogenous constituents of human milk after what has been 

 stated in connection with alimentation. The different constituents of 

 this class undoubtedly have the same nutritive office and they appear 

 to be identical in all varieties of milk, the only difference being in their 

 relative proportions. It is a matter of common experience, indeed, that 

 the milk of many of the lower animals will take the place of human 

 milk, when prepared so as to make the proportions of its different 

 constituents approximate the composition of the natural food of the 

 child. A comparison of the composition of human milk and of cow's 

 milk shows that the former is poorer in nitrogenous matters and richer 

 in butter and sugar ; and consequently, the upper strata of cow's milk, 



