Effect of Diet Producing Rickets in Rats. 269 



the protein, but in both fat soluble A, and possibly in its water 

 soluble B vitamines. The experiments summarized in Table IV 

 show the effect of the addition of various substances to the rickets- 

 producing diet. 



1. Four rats receiving an addition of 0.2 gm. of pasteurized 

 butter daily, developed rickets, the lesions being quite as severe as 

 those found in the control rats of the same litter maintained on 

 Diet 84 without butter. Further experiments are in progress, 

 using fresh unpasteurized butter. However, there is good reason 

 to believe that the butter used was adequate as regards its content 

 of fat soluble A. Ophthalmia did not occur in the butter-fed 

 rats, but was found in approximately 90 per cent, of the rats on 

 Diet 84 alone. Furthermore, a typical gain in weight was ob- 

 tained when this pasteurized butter was added to a fat-soluble 

 vitamine deficient diet. 



This experiment, we believe, adds further confirmation to the 

 data presented by Hess and his co-workers. In rats, absence of 

 fat soluble vitamine in the diet does not produce rickets, nor does 

 its presence prevent it. 



2. The addition of 60 mg. of "Harris yeast vitamine" daily to 

 diet 84 gave complete protection in 3 rats. The phosphorus con- 

 tent of this yeast preparation is so high that it comes within the 

 range which, in the form of an equivalent amount of phosphate, 

 would confer protection. Nothing definite can, therefore, be 

 deduced from this experiment, as to the possible protection at- 

 tributable to the water-soluble vitamine factor. It is interesting 

 to note that all three rats of this series showed ophthalmia. 



3. The addition of 10 gms. of purified casein to 100 gms. of 

 Diet 84 (containing phosphorus equivalent to the 72 mg. present 

 in Diet 85), gave results which are difficult to interpret. All three 

 rats of this series showed in the x-rays taken after 22 days on the 

 diet, distinct rachitic lesions. One of the rats, sacrificed on this 

 day, had definite rickets, grossly and microscopically. The other 

 two were allowed to continue to the 38th day, the x-rays taken at 

 death, showing an apparent healing of the rachitic lesions in the 

 head of the tibia. The microscopic study of the ribs in these 

 rats shows no active rickets. Further experiments are planned 

 to compare quantitatively the protection given by casein with that 

 given by inorganic phosphate. 



