1912.] 



The Metabolism of Lactating Women. 



101 



It seemed possible that the post-partum excretion of creatin might depend 

 on the metabolic changes taking place in the body which culminate in the 

 formation of caseinogen in the mammary gland at this period. It can 

 be well imagined that the demand of the mammary gland for specific 

 chemical groupings necessary for the formation of caseinogen itself might 

 result in chemical changes, particularly in the muscle, which would cause 

 the liberation of creatin into the blood-stream and its subsequent excretion. 

 If such were the case, then the addition of casein to the diet might render 

 unnecessary the creatin-liberating changes and effect a corresponding dis- 

 appearance of excreted creatin at this time. 



In the two following cases, 50 grm. of casein were added to the creatin- 

 free diet each day. 



It is evident that there is no diminution of creatin excreted as the result 

 of casein feeding, and the results lend no support to the hypothesis that the 

 metabolic changes involved in the formation of caseinogen by the mammary 

 gland are related to the post-partum excretion of creatin. 



5. The Independence of the Puerperal Excretion of Creatin and Carbohydrate 



Metabolism. 



The post-partum excretion of creatin is a good example of the fact that 

 there may not be anything, so far as is known, wrong or abnormal with 

 carbohydrate in the body while at the same time large quantities of creatin 

 are being excreted. 



Needless to say there is no acidosis in the case of a normal pregnancy, so 

 any relation between creatin excretion and carbohydrate is not so obvious 

 as such a condition would signify. For it is probable that all cases of 

 acidosis are accompanied by the excretion of some, although widely variable 

 amounts of, creatin. It seemed likely that the carbohydrate abnormality 

 responsible for the creatin excretion at this period was not an absolute 

 deficiency of carbohydrate in the body, but rather a sidetracking of certain 

 constituents of the carbohydrate in order to furnish an adequate supply 

 of lactose-forming substances to be dealt with by the mammarj 7 gland. 

 Consequently in the two cases now to be described lactose and dextrose 

 were respectively added to their otherwise abundant diets in order to satisfy 

 any glycogen and dextrose deficiency of the liver, and also the lactose 

 requirements of the mammary gland. 



It is obvious from these two carbohydrate-feeding experiments that if 

 there is any connection between carbohydrate and creatin excretion during 

 puerperium, it is obscure and of such a nature that alimentary carbo- 

 hydrate plays no part in the relation. In neither case — lactose feeding and 



