The determination of the antineuritic vitamin

Abstract

New methods are proposed for estimating the potency of substances containing vitamin Bi by means of tests in which (a) pigeons are cured of head retraction, and (b) the growth of rats is observed. The International Standard for vitamin K was used. The responses of 668 pigeons (duration of cure and percentage of birds cured) and of 150 rats -(growth) to doses of vitamin Bi were curvilinear. The 2 methods of calculating the potency of a substance by the use of pigeons gave the same results. Rats and pigeons gave the same result in an estimation of the potency of a soft extract of yeast in comparison with the International Standard, but on 2 samples of dried yeast, pigeons gave results which were double those given by rats. Thus pigeons and rats seem to be equally responsive to the vitamin Bi of the International Standard and of yeast extracts, but pigeons seem to be more responsive to the vitamin Bi of dried yeast than are rats. Statistically the degree of accuracy obtainable in these tests is very much greater for the rat tests than for the pigeon tests.