40 FEEDING EXPERIMENTS WITH ISOLATED FOOD SUBSTANCES. 



THE CASEIN DIET PROLONGED FEEDING TRIALS. 



The proportions of this food mixture (4, see page 33 ) thus tested 

 were therefore employed in subsequent experiments as a typical 

 "basal" ration. We record below the protocols of a few rats which 

 for many weeks have been kept in good health on this dietary with 

 pure casein as the sole protein. 



By an ill-advised plan these casein-fed rats were transferred dur- 

 ing one month to cages containing sand, and the estimation of the 

 nitrogenous excreta was omitted during this period. It was subse- 

 quently discovered that the animals ate more or less sand during 

 this time and we attribute the decline of weight and the subsequent 

 death in some cases to a resulting damage of the alimentary organs, 

 since sand was found in the faeces of some of the rats long afterwards 

 and autopsy showed great congestion of the intestinal tract. 



Table XXIII. Summary of Data on Rat 23, fed for 135 Days ox Pure Casein 

 as the only Protein. Diet 4, Page 33. Daily Averages. 



