A study of the incorporation of glycine-N(15) by chicken red cells in vitro has shown that: 1. There is no detectable nitrogen turnover in the histone or desoxyribonucleic acid of erythrocytes or reticulocytes. 2. Hemoglobin synthesis in the nucleated reticulocyte proceeds at 2 to 3 times the rate observed in the mature erythrocyte. 3. The uptake of glycine-N(15) by heme is 9 to 14 times the co...

Under normal circumstances, two members of the urobilinogen group have been identified in human feces and urine, both of which are determined quantitatively in the routine urobilinogen procedure (1). Of these, stercobilinogen predominates, while mesobilirubinogen occurs only in small amounts except during excessive hemolysis, when it has been present in sufficient quantity to permit crystalliza...

In Paper I in this series (2) the stimulation of penicillin production by certain compounds containing the phenylacetyl group was reported. It was realized that a stimulation of yield of this biological product following addition of a given substance to the medium may result from any one of several possible metabolic mechanisms. The stimulating substance may act as a vitamin or growth promoter,...