126 



PHYTOHORMONES 



Figure 42). The conception of Soding that growth cannot be 

 only plastic stretching and must involve also intussuscep- 

 tion is thus supported. 



X-ray analysis, however, has recently revealed the pres- 

 ence of a crystalline element other than cellulose which is 



-{-nj 



w 



y/) 



■n« 



ri^-|- \n, 



■ny 



n^cc-{-' -\-'n'r 



nr nj- 



rir 



nr 



no: 



n% na 



a b c d 



Fig. 41. Micellar structure of elongated cell-walls, a, fiber structure; b, 

 fiber-like structure; c, ring structure; d, tube structure. (From Frey-Wyssling, 

 Protoplasma 25: 261-300, 1936.) 



also present during elongation in Avena and in the cotton- 

 hair (Hess, Trogus, and Wergin, 1936). These workers 

 claim that in the cotton-hair the large crystalline aggregates 

 of cellulose which are responsible for the x-ray diffraction 

 patterns are completely absent during the period of elonga- 

 tion, while in growing Avena coleoptiles they are largely 

 confined to the epidermis. This, if substantiated, would 

 indicate that the importance of the larger cellulose micelles 



