VITAMINES 41 



their previous nutrition, or from idiosyncrasy, vary 

 in respect of their store of fat and its associated 

 vitamine. It is more difficult, therefore, in the 

 case of the fat-soluble factor to obtain completely 

 consistent results during experimental feeding. 

 Nevertheless all animals ultimately fail when this 

 factor is missing from their food. 



The probability is growing that there is one 

 disease — and it is a disease of serious import to the 

 'community — ^in which a dietetic error related to a 

 deficiency in the fat-soluble vitamine plays a causa- 

 tive part. I allude to rickets. We have in this 

 connexion, it is true, not yet the concordant evi- 

 dence from various sources which exists in proof of 

 the origin of beriberi or of the general importance 

 of vitamines. The case depends at the moment 

 mainly upon the remarkable experimental results 

 obtained by my friend and former pupil Dr. Edward 

 Mellanby : but his work is by no means without 

 the support of other evidence. It is easy, he has 

 found, to construct a diet upon which dogs, though 

 kept in healthy surroundings and given exercise, 

 speedily develop the characteristic symptoms of 

 rickets. It is easy to prevent this by suitable addi- 

 tions to the dietary, in particular by giving certain 

 fats. The fats which are specially efficacious are 

 those which, from other evidence, we know to be 

 rich in the fat-soluble vitamine. Vegetable fats, 

 free from the vitamine, are without efiect. The con- 



