FEEDING EXPERIMENTS WITH ISOLATED FOOD SUBSTANCES. 3 1 



0.05 



Chart X. Rat 12, fed on Dog Biscuit-Lard Diet for 84 days and then on Milk powder-Starch- Lard Diet 

 for 113 days. Numbers on Body-weight line indicate time at which each period began. 



DISCUSSION. 



The rats xxviii and xxix showed a steady decline on the dog- 

 biscuit-fat mixture (p. 13). In considering the quantity of food 

 eaten it must be borne in mind that the nitrogen content was rather 

 low (N= 1.65 per cent). 



Rats 10, 11, and 12 also showed, during the early period of the 

 experiment, a steady decline on the same diet, although it contained 

 more nitrogen . The temporary improvement shown after several weeks 

 at the point marked 3 indicates the introduction of a change in diet. 

 The improvement was, however, only temporary, as the charts in- 

 dicate. The curves of body-weight in these animals recall those 

 published by Falta and Noegerrath and correspond with the data 

 of other investigators mentioned above. They indicate the type of 

 experiment which is unsuccessful because of more or less obvious 

 insufficiency in food- intake or stored supply. In the case of rats 

 xxviii and 10, for example, this is pronounced and a steady and 

 continuous decline is noted. The decline of rat xxix, at first gradual, 

 became extremely marked with the striking decrease in the food- 

 intake at the end of the experiment. The other illustrations (rats 

 11 and 12) show intermediate types. As a rule, older, full-grown 

 animals exhibit slower decline than younger rats (of smaller weight) 



