338 GROWTH FACTORS AND FLOWERING 



the flowering response. An experiment with Hyoscyamus is shown 

 in Fig. 1. The auxin used in these original experiments was indole- 

 acetic acid. Since then, I have been able to obtain similar results with 

 indolebutyric acid and naphthaleneacetic acid (unpublished data). 



From these results, it might appear that auxin has opposite in- 

 fluence on photoinduction in short- and long-day plants: inhibitory in 

 the former, and promotive in the latter. Such a situation might be very 

 interesting. Short- and long-day plants respond to photoperiod in the 

 opposite manner. Their photoreceptors, however, appear to be the 

 same, and so do their floral stimuli. In view of this situation, one might 

 expect that in the course of the processes of photoinduction which 

 follow the initial photoreaction there appears a compound which has 

 opposite effects on flower stimulus formation in the two response 

 types. This compound would occupy a pivot position in the photo- 

 periodic "mechanism," and auxin, on the basis of the above results, 

 seemed to fit this position. 



A German saying goes, "One should stop eating when it tastes 

 best," and I suppose we should have stopped our work at this point. 

 However, we were ambitious and wanted to make the story perfect, 

 and in trying to do so we lost what story we did have. It turned out 



Table III. Effect of Applied Auxin and Antiauxin on Photoinduction in Annual 



Hyoscyamus niger 



Flowering Response, %" 



" Percent plants with flower buds. 

 ''Approximately 100 molar X 10~^. 



