18 



but the time required varied, the larger and less filzig 

 the leaf the more time was required for it to resume 

 its turgescence, 30 minutes being the average time. 



The following method was used to determine how 

 much the living hair cells contributed to this result, or 

 more strictly, to prove definitely that the walls of these 

 cells offered no more resistance to the entrance of water 

 than those of the epidermal cells, in which case it will 

 readily be seen that a far greater amount could enter 

 the hair cells and so find its way into the leaf tissue, 

 than could be taken in by the comparatively small sur- 

 face of the epidermis proper. 



A few drops of a ten per cent salt solution were 

 laid upon the filzig surface of a fresh, entire leaf, allow- 

 ed to remain four minutes, then a longitudinal section 

 through this part of the leaf was made and laid quickly 

 in oil, as little time as possible being consumed in the 

 operation in order to preclude the possibility of any 

 change in the water contents of any of the cells till the 

 oil could be applied, which would prevent any farther 

 change, at least, for a sufficient time to examine the 

 condition of the cells. Sections of the same leaf, cut not 

 far from the surface where the salt solution was applied, 

 were examined and the hair and epidermal cells found 

 to be in a normal condition, fresh, full and turgescent. 

 On examining the section treated with the salt solution, 

 nearly all the living hair cells were found to be plas- 

 molytic. In a few instances the cells of the epidermis 

 immediately in connection with these hair cells, were 

 also plasm oly tic, still fewer were in this condition that 

 were not connected with the hairs at all. 



This test shows that the water was drawn, by the 



