VITAMINS 281 



factor and a preventive of eye disease as was already 

 demonstrated, but was also the factor which determined 

 the proper deposition of lime salts in bone formation. 

 Mellanby believed it to be entitled to the term anti- 

 rachitic vitamin. The whole problem of rickets and its 

 prevention was then reopened. Much valuable new 

 data developed. It was found possible to cure rickets 

 by regulation of the phosphorus in the diet, by using 

 the ultra-violet ray or direct sunlight and by the use ot 

 cod-liver oil in the diet. The vitamin interest, how- 

 ever, centred about the use of the oil. Butter fat, 

 known to be rich in A vitamin, was shown to be value- 

 less as a preventive. On the other hand cod-liver oil 

 was shown to be many times richer in A than butter 

 fat and it was felt that perhaps Mellanby was right and 

 that the distinction was a matter of quantity in the 

 dosage. In August, 1922, however, McCollum pub- 

 lished a series of studies which seem to leave no other 

 conclusion than that cod-liver oil owes its antirachitic 

 power to a new vitamin, that the antirachitic vitamin 

 is not vitamin A. For this McCollum suggests the 

 term D unless it shall be shown conclusively that vita- 

 min B is actually composed of at least two factors. 

 Funk has already offered evidence that the B concen- 

 trates contain a factor which is essential to the cure of 

 beri-beri and another factor that seems to have a 

 specific power in stimulating yeast growth. For the 

 latter he had already suggested the term vitamin D. 

 McCollum raises the question as to whether we should 

 include in the vitamin series other factors than those 

 proved of significance in mammalian nutrition. This 



