168 CHEMICAL AGENTS AND GROWTH 



This compound gave an enormous increase which was the same in hght 

 and darkness, i.e., the effects of red and far red light were absent. 

 About this time Carter and Cohen (1956) suggested that adenylo- 

 succinic acid, which is simply adenylic acid with succinic acid replac- 

 ing; a hydrogen of the 6-amino group, could be converted to adenylic 

 acid. There is a further report that this compound occurs naturally in 

 mammalian liver (Joklik, 1956). The results of these workers led us 

 to try adenylic acid and other related compounds in our system, among 

 them, adenine. We found that adenine reacted in a manner analogous 

 to that of thiopurinesuccinic acid. The adenylic acid itself was not 

 very active, but this might be due to a lack of penetration into the 



Table III. Control of Leaf Growth by Light and Kinins — Increase in Diameter 



