1og. THE DETERMINATION OF VITAMIN B1 BY MEANS OF ITS INFLUENCE ON THE VAGINAL CONTENTS OF THE RAT BY KATHARINE HOPE COWARD AND BARBARA

THE influence of vitamin B1 on the vaginal contents of the mature rat has been examined with a view to using it as a criterion for the assay of that factor. Evans & Bishop [1922] showed that in the absence6f vitamin 'B' from the diet, the normal cycle of changes in the contents of the vagina was upset. No keratinized cells were found and leucocytes with some nucleated epithelial cells were found day after day up to the time of death of the animal. This was confirmed by Macy et al. [1927]. Up to this time vitamin 'B' had not been proved to consist of several factors and our first experiment showed that this upset of the cycle of changes in the vaginal contents could be brought about by a deficiency of vitamin B1 only. A later experiment showed that it could also be brought about by a deficiency of riboflavin only. The regular cycle could in either case be restored by giving the missing factor. The main part of the work showed that after a deficiency of vitamin B1, the response to vitamin B1 was graded to the dose given, i.e. the larger the dose of vitamin B1 given the more quickly was the normal cycle of changes restored. Thus it would be possible to use this property of vitamin B1 for its assay, but the accuracy obtainable by its use proved to be less than that obtainable by the 'rat growth' method.