﻿plant exposed to an artificial rainfall and 

 cause a reaction by a puflf of the breath. 



When a plant has become accustomed to a 

 continuously acting force, the amount of in- 

 crease necessary to secure a reaction is a defi- 

 nite and fixed proportion of the continuously 

 acting force. The formula which expresses 

 this proportion has been found to apply to 

 the reactions of both plants and animals. 



The manner in which impulses are trans- 

 mitted from one part of a plant to another Method 

 forms a problem, the solution of which has of transmission 

 baffled investigation for more than a century. 

 Many interesting experiments looking to- 

 ward a determination of the question have 

 been made. 



It has been found that when a section of a 

 stem has been girdled by the removal of the 

 bark and cambium the transmission of an im- 

 pulse is in nowise hindered, thus proving 

 that the path lies through the wood, which 

 in this plant is composed of cells which die on 

 attaining normal size. The fact is proven 

 more positively by the removal of the wood 

 from another section, the living tissues and 

 bark being allowed to remain. In this in- 

 stance no transmission occurs. 



If a short section of a stem is killed by 

 means of a bandage of cloth kept saturated 

 with boiling water for several minutes, trans- 



