Mathema Tics: N. Aronszajn

occurrence of characteristic effects of genes on viability8 and on shape of the spermatheca9 in Drosophila seem to suggest that this is the case. Summary.-The tryptophane content of aa Ephestia larvae is higher than that of a+a+ Ephestia larvae in the non-protein fraction and probably also in the protein fraction. In homogenates of isogenic a+a+ and aa homogenates, autolysis proceeds at a faster rate ina+a+thaninaamaterial. Formation under the influence of the gene a of a protein richer in tryptophane and more resistant to proteolytic enzymes would constitute a conceivable mechanism for inhibition of kynurenin formation in aa animals.