120 Percentage CoinposUioit of Milk 



It will be seen that jn no case was there a direct increase in the per- 

 centage of that constituent of the milk corresponding to the constituent 

 of the diet which was present in excess. The protein, fat and ash all 

 tended to vary, albeit to different degrees, inverseh-, and the lactose 

 directly, as the daily volume of milk secreted. It is true that with the 

 different diets variations in the percentage composition of the milk were 

 produced, but these variations were of such a nature, and took place 

 to such a degree, as could be accounted for by the variations in the rate 

 of secretion, and, therefore, in the daily volume of the milk. 



Fig. 4 brings out very clearly the direct relationsiiip existing between 

 the percentage of lactose and the daily volume of milk secreted. 



Several different feeding experiments were carried out with, in every 

 case, results similar to those stated above. In one of these it was con- 

 sidered that a high protein diet had markedly stimulated the rate of 

 milk secretion. In this experiment, tliercfore, it is worthy of note, the 

 high protein diet was made up in such a way that it was of lower calorific 

 value than either the high fat diet which preceded it, or the high carbo- 

 hydrate diet which followed it. The greatest secretion of milk, however, 

 was got on the diet of lowest calorific value, viz., the high protein diet. 

 The following are the main features of the diets set out against the average 

 daily volumes of milk obtained. 



Volume of 

 C'aloritiu value of diet milk 



High fat diot ... 4230 calories (containing 136 gms. 400 c.c. 



of fat) 

 High protein diet ... 3700 calories (containing 305 gnis. 540 c.c. 



of protein) 

 High carbohydrate diet 4630 calories (containing 933 gms. 440 c.c. 



of carbohydrate) 



There is one constituent, however, not of the milk but in the milk, 

 the percentage of which was found to have a direct relationship to diet, 

 viz., the non-protein nitrogen. This was estimated by the difference in 

 the figures for the percentage of total protein and the sum of the per- 

 centages of casein, albumin and globulin. Wliilc not protein, therefore, 

 it is expressed separately in terms of protein, in view of the fact that 

 it was included in the estimation of nitrogen from which tfie percentage 

 of total protein was calculated. It was found to vary from about 0-1 

 per cent, to 0-4 per cent, with the amount of protein taken in the food. 

 (This is being dealt with in another })ubUcation.) 



