Preiss and Klein-radiation Energy Loss in Seed Layers

than those for 100 % curves. Since there exists no non-decreasing functional relationship between germination percentage and energy loss in this region, ionizations in the fruit coat cannot be responsible for the induced germination. Likewise, in the region of the embryo there is a 69 % germination curve which lies above a 100 % curve. (In both of these cases visible embryo damage could be seen.) Therefore, germination increase cannot be ascribed to ionization effects in the embryo. However, the required functional relationship between germination percentage and energy loss is satisfied in the endosperm region (fig 3). The points on this curve were obtained by integrating the five rate curves of figure 2 from 7 to 16.5 ,u. It can be concluded that a sub-surface shell-like region of the seed exists where ionizations induce germination. The measured values of the stopping powers of the outer seed layers relative to a standard protein absorber allow us to identify this region as the endosperm.