CHANGES IN COMPOSITION OF BODY OF RAT 



25 



directly a sufficient quantity of milk for investigation. I have 

 therefore decided to follow a somewhat indirect method and to 

 examine the stomach contents of young rats that are taking 

 mother's milk exclusively. Although the composition of the 

 stomach contents may not exactly represent that of normal 

 milk, nevertheless by care in collecting it before it has been 

 acted on by the gastric juice for any length of time, we may 

 yet obtain some useful information. The following is the 

 table showing the chemical composition of the stomach contents 

 which had been carefully collected from the rats one to fourteen 

 days old. 



TABLE 1 



Showing the composition of the stomach contents of the young rats which are taking 



mother^s milk 



I give also in table 2 the data on the chemical composition of 

 the milk of several other mammals (compiled from the data 

 given by Konig '03) which may be compared with that of the 

 albino rat. 



The comparison reveals the fact that the 'milk' of the rat is 

 highly concentrated, and thus the content of the fat is remark- 

 ably high. Whether or not this high concentration of the milk 

 was due to a rapid elimination of water from the stomach to 

 the lower part of the digestive tract, cannot be determined, though 

 I may remark in this connection that the absorption of water 

 through the stomach wall is insignificant, and at the same time 

 the gastric secretion must tend to increase the water. It appears 

 therefore that this high concentration of the milk noted above, 

 might after all indicate a normal condition of the fresh milk. 



