For more than a decade the antineuritic principle has been designated as vitamin B, but developments of the past two years have imparted to the latter term an ambiguity that has led to much perplexity. Not only is the chemical nature of vitamin B still unknown, but just what should be included under the term has become largely a matter of individual preference or persuasion. It is not without interest to trace the varied changes which the concept of this vitamin has undergone. What was originally the antineuritic substance of Eijkman and Funk,1 which was a specific for the cure of polyneuritis in pigeons, and what was the independently discovered water-soluble B of McCollum,2 which was demonstrated to be necessary for growth in the rat, became merged into the substance vitamin B,3 following the demonstration that those natural foods curing polyneuritis likewise promoted growth in animals.4 Thus vitamin B was regarded as one substance, capable of both preventing polyneuritis and furthering growth. But the simplicity of the view was dispelled by convincing evidence that this vitamin actually comprised at least two substances, differentiated on the basis of sensitivity to heat.5 After a period of utmost confusion in terminology, agreement was finally reached in this country e by designating the antineuritic, thermolabile component as vitamin B, and the antidermatitis,7 thermostable substance as vitamin G. The British, preferring the subscript system, retained the names Bj and B, for the respective fractions. As the result of this insight into the multiple nature of water-soluble B, there was no longer a water-soluble B growth factor per se; both components, B and G, were deemed necessary for increase of weight in rats.At once it was appreciated that much of the vast accumulation of facts concerning the distribution, properties and physiologic behavior of vitamin B, recorded when it was held to be a unit substance, would have to be exhumed and reexamined in the light of its dual nature. For the production of uncomplicated vitamin B deficiency, the method now usually involved inclusion of autoclaved yeast as a source of vitamin G in the basal diet. But the provision of vitamin B alone was not so readily achieved because of its instability to heat and because so relatively few foodstuffs contained it to the exclusion of vitamin G. However, by suitable selection of such grains as wheat and corn, which were found to be relatively richer in B than in G, and by taking advantage of the greater solubility of B in strong alcohol, extracts were prepared containing predominantly the B component. With the perfection of this technic, investigations on vitamin B were renewed with an intensity that even yet has only slightly abated. But new complications appeared with the use of moderately refined concentrates of vitamin B, because these products, while curing polyneuritis, very often would not support growth, even when supplemented with a source of vitamin G. So, almost before the novelty of the dual nature of the B complex had wo...
