366 



K. V. Thimann and N. Takahashi 



Fig. 1. Increase in fresh weight of potato tuber disks in water, in l-naphtha- 

 Icneacetic acid, 1 mg/1, or in 1-naphthaiencacctic acid, 1 mg/1 with 10-^\/ CoCL. 

 Data courtesy Kenneth Wright. 



\0-^'M, is the same as with Avena. The promotive eliect, though not 

 quite as large as witli Avoia and Pisinn, is clear enough. It will be 

 noted that promotion of growth by cobalt appears as soon as promo- 

 tion by auxin does, and that its effect is exerted dining the period 

 of most rapid growth. Thus, there is no indication here of a delayed 

 effect like that just mentioned. Also, in our experiments with galac- 

 tose, cobalt was found not to interfere with the conversion of this 

 sugar to wall material (22). 



Even with the Avena coleoptile our results do not indicate a 

 delay of more than 12 hours in tiie onset of the cobalt effect (Figure 2). 



