Physiology: Tyler and Horowitz

times that needed to denature egg albumin, using the estimate given by Mirskyl2 or fifty times the energy needed for the inactivation of certain ionic forms of pepsin according to Steinhardt's determinations."3 The denaturation of egg albumin by ultra-violet light is a first order reaction,'4 i.e., the survival curve is a straight line similar to that obtained for chromosome abnormalities. It seems quite likely, therefore, that denaturation may occur in the production of chromosome abnormalities by x-rays. In this connection it is interesting to note that abnormally high temperature will produce chromosome abnormalities. Also, with incompletely ripened V. faba seed that have thin seed coats, the frequency of chromosome abnormalities will gradually rise from 1 to 30 per cent in two months, suggesting that the process may be due to desiccation or oxidation. All these agents will denature proteins.