136 



GROWTH HORMONES IN PLANTS 



6200 5780 5460 4360 4050 3660 



Wave length in Angstroms 

 Fig. 43. — Spectrum sensitivity curve of phototropic response (solid line) 

 and protoplasmic streaming (points) in the Avena coleoptile. The agreement 

 between the phototropic response and the effect of light on retarding proto- 

 plasmic streaming suggest an interrelationship. (After Bottelier, 1934.) 

 {Curve of phototropic response from Blaauw, 1909.) 



5400 



5200 



5000 



4400 



4200 



4000 



4800 ^ 4600 



Wave length in Angstroms 



Fig. 44. — Curve of inhibition of Lactuca seed germination (solid line) in the 

 violet-green region compared with the curve of phototropic response of Avena 

 coleoptiles (broken line). {After Flint and McAlister, 1935.) (Curve of photo- 

 tropic response from Johnston, 1934.) 



