On blood-platelets: their behaviour in “vitamin A” deficiency and after “radiation,” and their relation to bacterial infections

When the fat-soluble vitamin A is withheld from the diet of a rat, the general condition of the animal differs from that resulting from a deficiency of the water-soluble B vitamin. In the latter case the animal ceases to increase in weight almost at once, and then begins to decline. There is a progressive fall in the temperature. The animals always die within a comparatively short time-two months-and are then found to be in a state of profound emaciation, as if they had received no food at all. There is no obvious sign of disease or of an infection. For the sake of convenience, we will designate briefly this condition by the term “marasmus.” The withholding of the fat-soluble vitamin A alone affects different individual rats in a manner as varied and indefinite as the conditions obtained by a deficiency in the water-soluble B are constant and definite. When a young rat is kept on a diet from which the fat-soluble vitamin A is absent, the increase in weight may cease almost at once, or it may continue to increase in weight for many weeks, and almost as rapidly as on a diet containing vitamin A, although eventually its growth will come to a standstill before the full normal size of the adult rat has been reached. We shall, for the sake of convenience, describe these two extremes as the “acute” and the “chronic” effect on growth respectively. Eventually the rats develop infective conditions, which attack most frequently the eyes, and xerophthalmia develops. There may be other organs affected (septic glands or pneumonia sometimes develop).