346 CARNEGIE INSTITUTION OF WASHINGTON. 



light of current studies on rickets and other bone disorders associated with 

 dietary deficiencies. PreHminary results which we have already secured by 

 limiting the total intake of a qualitatively satisfactory salt mixture, in an 

 otherwise adequate diet, point to the possibility of producing more or less 

 permanent defects from which recovery is not as readily possible by increasing 

 the quantity of the minimum component as seems to be the case with respect 

 to other dietary factors. Usually when an animal fails to grow normally 

 because of a shortage of protein, for example, in an otherwise adequate 

 ration, an increased supply of good protein will bring about prompt recovery. 

 On the other hand, in experiments in which the total admixture of our satis- 

 factory salt mixture has been limited to 0.5 or even 1 per cent of a food such as 

 we have been accustomed to employ, and the animals have failed to grow well 

 because of this limitation, complete recovery and satisfactory growth have as 

 yet in no case ensued when the percentage of salt mixture has been increased 

 to the conventional proportions. Why restoration is less readily accomplished 

 by feeding a suitable ration after an animal has been limited with reference to 

 its intake of inorganic nutrients alone deserves careful consideration. The 

 possibilities of physiological damage in this way may be not inconsiderable in 

 the case of man, who is gradually becoming accustomed to refinement and 

 alteration in his natural foods, and ordinarily takes no account of the possible 

 limitations of the inorganic ingredients of his diet. 



