VITAMINES 237 



of the fat as fat contained in the cod liver oil ? Is it not more 

 likely, as Casimir Funk has pointed out, that a " vitamine " 

 present in the cod liver oil was really the active agent in 

 bringing about the cure ? From the chemical standpoint it is 

 difficult to see how the presence or absence of fat — an organic 

 compound containing a store of energy liberated in the body 

 by breaking down into carbon dioxide and water — can affect 

 the laying down of calcium salts in the bony tissues or in any 

 way bring about the collateral symptoms of rickets. We know 

 that a child may be brought by starvation to death's door 

 without having shown any sign of rickets, and conversely, it 

 is common knowledge that it often is the fat, overfed child which 

 suffers from the complaint. If rickety children may have a 

 superabundance of fat, how can the lack of it be the cause of 

 the disease ? As a matter of fact, experience has shown that 

 children, and lion cubs, may recover from rickets and grow 

 up without the addition of any special fatty constituents to 

 the diet. 



We have seen that the error in scurvy is the absence of a 

 minute quantity of essential vitamine and not the lack of any 

 of the physiological classes of foodstuffs. It seems probable 

 that rickets also is due to the absence of a vitamine which 

 associates itself with the fatty portion of the diet. If fat be 

 removed from milk, and the child be fed on the skim milk, 

 rickets will probably ensue because the vitamine has also been 

 removed. But it is not necessary to remove the fat to produce 

 an unsuitable diet. Simply boiling the milk will produce the 

 same effect, although the fats are thereby practically unaffected. 

 It cannot, therefore, be lack of fat that accounts for the outbreak 

 of rickets, but, instead, the absence of a vitamine similar to 

 those responsible for the prevention of beri-beri and scurvy. 



Accessory Substances Necessary for Growth 



Recent work has revealed the presence of traces of sub- 

 stances in food which regulate the growth of young animals. 

 The discovery of these substances was made by Gowland 

 Hopkins during a series of experiments which had for their 

 object the maintenance of animals upon artificial mixtures of 

 pure carbohydrates, fats, proteins, and salts. The researches 

 of Gowland Hopkins in this country, Osborne and Mendel in 



