In the field of nutrition the absence of the "B" type is particularly marked by the behavior of the deprived animal. Rats transferred from a vitamine-free diet to one containing the "B" only, make a much more rapid recovery toward normal (even in the absence of the "A") than do animals transferred from the vitamine-free diet to one containing the "A" and not the "B". This initial jump from addition of the "B" will not continue long in the absence of the "A", as a general rule. Hess believes that in some of his infants he was able to show markedly successful growth on the diet deficient in the "A" but rich in the "B". It is not certain however that his diets were sufficiently devoid of the "A" factor to be declared "A" vitamine-free and we know little of the amount of the "A" necessary to normal infant growth. All results however show that both "A" and "B" are necessary to growth production and though the term growth vitamine was applied to the "A" originally the distinction is one that should be rejected, for both "A" and "B" and possibly "C" are all entitled to this name. The manner in which the "B" vitamine acts is still obscure. Voegtlin some time ago tried to demonstrate that it was identical with secretin and stimulated pancreatic flow. Recent work at the Johns Hopkins University by Cowgill and by Aurep and Drummond in England has failed to confirm this. One of its most marked immediate effects is increase in appetite. Karr in Mendel's laboratory has shown that dogs which refused their basal diet would resume eating it if they were allowed to ingest separately a little dried yeast. Karr studied the metabolism of these dogs as regards nitrogen partition but the results give little data that is explicatory of the behavior of the vitamine. In 1915 the author was able to bring about marked immediate improvement and the ultimate recovery of a number of infants who were of the marasmic type by merely increasing the "B" vitamine content of their food. In these cases the vitamine was carried by Lloyd's reagent and administered mixed with cereal, or the crude extract was combined with the milk. The pancreas of the sheep was the source used. In these cases the growth curve changed abruptly from a decline to a sharp rise and this increase in weight continued and was accompanied by all the other signs of improved nutrition including increase in appetite. The change in the growth curve from decline to rise was accomplished without increasing or changing the basal diet but as the appetite increased the food had naturally to be increased to keep pace. In these cases the effect of the vitamine was to enable the child to utilize its normal food and to increase its appetite for it. This action certainly suggests stimulation of digestive glands. It also showed that even though the diet may contain the vitamine as was the case in the milk fed to these children the addition of the vitamine in concentrated form often gives an upward push