Abstract
By means of Barker and Summerson''s method the free acid present in the vaginal lumen of the rat (25 rats 5-6 mos. old were used) was found to be lactic acid. The amt. increased rapidly during diestrum, decreased somewhat in early estrus and reached a 2d maximum in full estrus (at time of ovulation). The significance of this 2-peak curve is discussed in relation to present knowledge of the cycles of glycogen deposition and of mitotic activity in the cells of the vaginal epithelium.