19 — 



force of the solution, through the cell walls of the hairs 

 more readily than through those of the epidermis, as 

 there were comparatively few instances where it had 

 acted on the epidermal cells. 



The only objection, which can be urged against the 

 accuracy of the method is that it is possible for the 

 solution to act on the cut surface of the leaf, during the 

 time elapsing between making the section and applying 

 the oil, thus drawing the water out through the uncuti- 

 cularized walls of the leaf tissue instead of those of the 

 hair cells. That this objection has but little weight is 

 shown by two considerations. First: were this the fact, 

 the water would have to be drawn through several walls, 

 as 4, 3, 2, 1 (in the figure) before the cell d could lose 



enough to become plasmolytic. 

 In many instances the cell d 

 (or cells similarly situated) was 

 plasmolytic, while those below 

 c b a were normal and tur- 

 gescent. Secondly : If the plas- 

 molyse of the hair cells was 

 accomplished by the water es- 

 caping into the cells below and 

 then from these cells, all the 

 epidermal cells not connected 

 with the hair cells, being subjected to the same influence, 

 would have suffered loss of water in the same way; 

 but in all the numerous sections thus tested nearly all 

 of these cells were full and turgescent. 



The experiment was repeated several times and al- 

 ways with a similar result; in various other ways the 

 same conclusion was reached, fresh sections were laid 



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