﻿drostatic disturbance. As a matter of fact 

 impulses have been conducted through air-dry 

 wood of the stem in which hydrostatic trans- 

 mission would be impossible, and the only 

 pathway would be the water of imbibition in 

 the cell wall. Information as to the condi- 

 tion of water in the wall is not sufficient to 

 make the formulation of any reasonable 

 theory based on this assumption possible. 



The reaction of mimosa to impact and 

 injury is supposed to be a protection against Purpose 

 drouth and damage from grazing animals, ^^'^^^^tion 

 A recent writer says: "When a browsing *° "^^^^^^ ^t^- 

 animal approaches a clump of mimosa and 

 agitates any part of it at all strongly the 

 green appearance disappears at once, and only 

 an apparently withered clump in which the 

 hard and prickly stems are most conspicuous 

 remains ; the consequence being that the ani- 

 mal either turns away or passes through the 

 clump to less bewildering pasturage." 



As the plant has not been studied in its 

 habitat in Venezuela and Brazil it is not 

 definitely known whether it is ravaged by 

 grazing animals or not. The theory was 

 once proposed and widely reiterated that the 

 contact irritabihty of mimosa was developed 

 as a protection against hailstorms, regardless 

 of the fact that the plant never encounters 

 such dangers in the torrid zone. As has been 



