I am unable to see the logic of Voegtlin's reasoning. An alcoholic extract of liver would not modify the inorganic content of diet X, nor the biological value of its proteins. The content of diet X in the anti-neuritic, anti-scorbutic and fat-soluble A factors, when compared with ordinary standards, would seem to be moderately satisfactory. Poor quality of protein and relative shortage of the anti-scorbutic substance were the two deficiencies which anyone familiar with modern nutrition studies would suggest on inspecting the formula of this diet. The extract of liver would contain an abundance of two at least unidentified dietary factors, but would not improve the diet in respect to the two known deficiencies. For the rat, at least, it is certain that diet X would be supplemented by the addition of purified protein and mineral salts, so as to be entirely adequate for nutrition of young animals during growth, and for the maintenance during many months of fairly good vigor in the adult. For this species, therefore, there is no necessity for postulating the need of a supplementary addition of a hypothetical anti-pellagra substance. It seems that if liver extracts are found so effective in supplementing the diet on which the condition of patients remained stationary, or grew worse, the explanation to which one must be tentatively driven is that Funk's hypothesis that pellagra is actually a specific deficiency disease must be correct. Certain it is, however, that Voegtlin is illogical in trying to hold simultaneously to two views, viz.: that there is something in an alcoholic extract of fat-free liver which cures pellagra, when it is made to supplement diet X, and that the syndrome is caused by a combination of the deficiencies in some of the well-recognized food factors.

In the preparation of the liver and thymus extracts Voegtlin and his co-workers extracted the dried glands with alcohol at room temperature, and after filtration a considerable part of the alcohol was evaporated at 35°- 40° C. in vacuo. The viscous substance remaining was extracted twice with ether in a sepa-ratory funnel. Three layers formed: an upper layer consisting of ether containing fats and lipins; a middle layer consisting of white or yellowish insoluble residue, and a lower layer consisting of a mixture of substances of oil-like properties. The last-named layer was designated as the "vitamin fraction." In the treatment of adult pellagra patients, daily doses of this oily material equivalent to one kilogram of fresh liver or thymus were administered.