Chemical induction of growth 



and presumably occur in all such similar materials, which 'are nitrogen 

 free. This surprising result has led to the recognition that the general class 

 of substances to which some of these materials belong is the leucoanthocyanins. 



en 



60- 



W~ 



Carrot A 



□ Minus casein hydrolysafe 

 ^ Plus casein liydrolysate 



i 



03 



5i 20 



•^ 





fK 



; 



J 



i 

 i 



Corrof B 



T ", 







i 



■: 



Basal 

 medium 



Basal 



t C-lli. 



O-BVc OIBVc 0032''Io 

 Basal f Aesculus endosperm 



Figure 8. Effect of liquid endosperm from immature fruits o/" Aesculus woerlitzensis on the growth 

 of carrot phloem explants, compared with growth in basal medium and in basal medium plus 1 per cent 

 coco-nut milk. 



The reasons for arriving at this conclusion are briefly summarized, 

 although the full data cannot be recorded but will be reserved for the time 

 at which one or more of these substances is unequivocally and finally 

 identified. It may, however, be stated clearly that in the immature Aesculus 

 fruit a large part of the growth-promoting activity can be ascribed to a 

 leucoanthocyanin which may be a complex monoglucoside with one of the 

 general chemical formulae indicated below, based on structures proposed by 

 (a) Robinson and Robinson (1933), and {b) Swain 



HO 



OH 



H 



OH 



O 



c- 



.OH 

 — OH 



HO 



CH-O-CsH^O^ 



OH 



(a) 



OH 



OH 



I 



-OH 



H /CH — O — CjHijOs 



OH 



(b) 



Figure 9. Structure of Leucocyanidin monoglucoside suggested by {a) Robinson and Robinson (1933) 

 {b) Swain (1954). 



183 



