NO. 20 GROWTH SUBSTANCE BURKHOLDER AND JOHNSTON 



GHT 



Fig. I. — Method of diffusing growth substance into agar blocks 

 from split coleoptile tips illuminated unilaterally. 



Table 5. — Influence of Radiation on Grozvth Substance 

 Excised tips illuminated laterally (Avcna and Zea mays) 



'Average of 18 tests. 



