248 Transactions of the Canadian Institute. [Vol. V'II. 



III. — Absorption of Water by Foliage Leaves. 



The experiments relating to this subject were designed to determine 

 whether detached leaves and cut shoots could absorb water. Four 

 series of experiments were arranged. For the first series the leaves 

 were collected on June 6th, at 4 p.m.. and allowed to wilt until 9.30 

 a.m., June 7th, when some of them were placed in distilled water and 

 left immersed for twenty-four hours. The others were similarly 



immersed six hours after the first, and left 

 for eighteen hours (Fig. 2). The second 

 series of experiments was with cut shoots, 

 1 and was conducted similarly to the first, 

 ^^^' ^; excepting that no weighings were made. 



Leaf immersed in water, P. a , i • i i • i i 



strip of litmus paper. The thu'd was to test absorption by the 



petiole. The fourth series was designed to 

 test by measurement the amount of water absorbed by a leaf under 

 conditions such as are shown in Fig. 4. 



Immediately after the leaves (series I. and II.) were immersed, 

 a small strip each, of red and of blue litmus paper was laid on each leaf 

 at a point where part of the leaf was close to the surface of the water 

 (Fig. 2). This was to determine if acids or alkaline substances left the 

 leaf tissue to enter the surrounding water, for if such substances did so 

 at was not unreasonable to suppose that this indicated that the water 

 from the vessel had entered the tissue of the leaf according to the laws 

 of diffusion. 



The question of the passage of neutral salts through the epidermal 

 tissue under similar conditions is discussed in Chapters IV. and V. 



It is thought that the weighing of the leaves before and after 

 immersion would not of itself decide the question, because it is impos- 

 sible to know that the leaves are externally in the same condition 

 as when weighed previous to immersion ; and, moreover, as the leaves 

 are constantly changing in weight by losing water by evaporation, very 

 accurate quantitative results are not easy to obtain. Since substances 

 are extracted from leaves by the application of distilled water (Chapters 

 IV. and v.), account of this must be taken in the weighings. 



In order to bring out more prominently the results it was thought 

 well to use a scale of numbers — 12 . . . . o, the number 10 indicating 



