Anti-Rachitic Substances 



377 



by means of a method which can reasonably be expected to give 

 results, we have been unable to confirm the assumption that green 

 leaves and a number of other food materials contain a significant 

 amount of anti-rachitic substance. 



How then are we to explain the results of McCollum and 

 others that butter and cocoanut oil produce partial cures. The 

 following experiment, we think, throws light on the subject : 

 When rats are kept for four weeks on a diet of flour and a salt 

 mixture containing 2.9 per cent, of calcium lactate, rickets is 

 regularly produced. When we use this diet with the addition 

 of 20 per cent, of either cotton seed oil or crisco, a hydrogenated 

 product from cotton seed oil, rickets is still produced. If, how- 

 ever, we lower the percentage of calcium lactate to 1.5 per cent., 

 the diet without fat produces rickets, while the addition of 20 

 per cent, of crisco entirely prevents it and the cotton seed oil 

 does not prevent it but merely gives a somewhat lesser degree 

 of rickets. In this case vitamin action is excluded, but we find 

 that the hydrogenated product prevents rickets. The hydro- 

 genation has increased the melting point of the oil; and the 

 soaps from crisco are more insoluble than those from cotton 

 seed oil. Our interpretation is, that in the case of crisco more 

 insoluble calcium soaps are formed in the intestines and by pre- 

 cipitating calcium soaps phosphate in soluble form which w T ould 

 otherwise be precipitated as calcium phosphate is made available 

 for absorption. With a great excess of calcium in the diet 

 containing 2.9 per cent, of calcium lactate, the precipitating 

 action of crisco is, however, insufficient to prevent rickets. Now 

 if we turn back to cocoanut oil, we can easily see how this fat 

 whose soaps are notoriously insoluble will show such a marked 

 rickets preventing action. 



We also see from this experiment that the rickets producing 

 qualities of a diet depend on the exact adjustment of quite a 

 number of factors, and we are led to believe that the slight 

 rickets curing action of butter recorded by McCollum is due to 

 fatty acids in the butter rather than a vitamin, particularly since 

 we are unable to obtain any concentrated active substance from 

 butter, and since after all rickets in infants cannot be prevented 

 or cured by either butter or cream. 



While we cannot say that we have proved the non-existence 

 of an anti-rachitic vitamin the facts adduced certainly detract 



