nybom: vegetativelv propagated species 



265 



still unpublished work of Shapiro (103) carried out at the Brookhaven 

 National Laboratory with roses, chrysanthemums, geraniums, and 

 gerbera. 



Mutation Experiments at Balsgard 



As briefly as possible, I should like to account for the mutation 

 experiments on fruit trees and small fruits carried out at my own 

 station at Balsgard. In cooperation with The Swedish group for 

 Theoretical and Applied Mutation Research, we have now mutation 

 material under way of most of the plants we work with at the Station. 



Since 1952, we have had stationary cobalt 60-sources for irradi- 

 ation purposes. The old one, shown in Figure 1, was enclosed in a 

 metal tube inserted into the ground. This source was removed last 

 year and we are now installing another one, shown in Figures 2 and 3. 

 As we have not found any advantage in the chronic irradiation of 



Figure 1. — Fruit trees being irradiated at the old cobalt source. Arrow 

 indicates the position of the source. 



