44 



BOr.4AVC.4Z. GAZETTE 



(JANUARY 



vi. Further variation of these experiments 



It is well known that the so-called geo tropic "stimulus" goes 

 around a corner, that is, around an incision. If we assume that 

 the so-called "stimulus" is the flow of a liquid, we need not be sur- 

 prised that it is able to go around a corner or around an incision in 

 a stem. In a former paper (see footnote i) we have shown that 



I 



the "inhibition" of the stem upon the growth of the notches of a 



Fig. 26 



leaf also goes around a corner in a leaf when incisions are made into 

 such a leaf; and the mysterious character of the phenomenon dis- 

 appeared with the recognition of the fact that the "inhibition" is 

 the flow of certain substances (water or solutes) from the leaf into 

 the stem through a system of interlinked channels which allows 



a flow in a zigzag around incisions. 



same conceDtion will 



ain in our opinion why a geo tropic "stimulus" will flow around 

 ncision in a stem, the "stimulus" like the "inhibition" being 

 flow of certain substances through the leaf or stem respectively, 

 [ncisions were made into each internode of stems of Bryophyllum 



stems 



calycinunty at a, b, c y and d in figs. 28 and 29. The 



pended horizontally in a jar saturated with water vapor 



Six 





1 



t 



