SKOOG AND TSUI 267 



TABLE 2 



Effect of adenosine on bud formation in tobacco callus cultures. (White's 

 medium, 3/4 strength. Experiment started 9/23/43, measurements made 



1/1/44-) 



*Cultures in the last column received increased concentrations of the following 

 components of the basic medium: KH^PO^, 5 times (62.5 mg./l.); Fe2(S04)3, 3 

 times (7.5 mg./l.) ; and sucrose 2 times (40 g./l.). 



responses to treatments with adenine and lAA or NAA. It was, therefore, 

 chosen for detailed studies of the effects of the above compounds on 

 growth and organ formation. These include measurements of effects of 

 added growth substances and nutrients as well as quantitative analyses 

 of associated changes in composition of various constituents and nutrients 

 within the tissues. The work is still far from complete, but the results 

 reported here are based on our present experience with about ten 

 thousand cultures. 



Representative results of the effects of the different treatments with 

 relatively high adenine and low lAA concentrations on growth are shown 

 in Figure 2, and results of anatomical studies, carried out by Dr. Sterling, 

 on these tissues at successive stages of their growth are summarized by 

 the diagrams in Figure 3. 



TABLE 3 



The effect of adenine sulfate on bud formation of tobacco calli obtained in 



first transfer (on 6/18) from stem internode segments cultured for 29 days. 



Cultures started in liquid media 6/18/48. Measurements 7/21/48 



Concentrations of Number of Number of calli Number of 

 adenine sulfate calli observed forming buds buds formed 



o (control) 27 o o 



2.5 mg./l. 30 4 4 



5 mg-/l- 30 6 10 



10 mg./l. 21 7 14 



No root formation occurred. 



