654 



QUANTITATIVE LAWS EST REGENERATION. II 



Figs. 2 and 3 show the distribution of the reddish pigment formed 

 in the leaves suspended in air and drying out. The reddish pigment 

 is indicated by the stippled area in the leaf. In the two leaves con- 

 nected with a piece of stem where the regeneration of shoots in the 

 leaf is inhibited the pigment flows into the stem and the newly form- 

 ing shoots in the stem. The old leaf contains pigment only in that 

 part which is close to the petiole and this is obviously pigment in 



Fig. 1. Leaves suspended with apex in water. Inhibitory influence of a 

 piece of half stem on shoot and root formation in leaf connected with it. The 

 leaf to the right (without stem) has formed three vigorous shoots and numerous 

 roots. The sister leaf with a small piece of split stem attached has formed in the 

 same time a tiny shoot and a few roots. The material required for root and shoot 

 formation in the leaf has migrated into the stem and gives rise there to an axillary 

 shoot and to the growth in the stem indicated by stippling. Duration of experi- 

 ment, Mar. 30 to Apr. 27. 



