3i6 



Transactions of the Canadian Institute. 



[Vol. VII. 



of plants, one must examine into the condition of the leaf surface, 

 because this surface might exert a mechanical influence upon the 

 solution. Plants whose leaves are coated with an oily or waxy- 

 substance will shed the 

 liquid applied, while other 

 plants which apparently 

 shed the drops, actually 

 spread the liquid over the 

 veins by the capillary 

 action of the hairs and 

 striations which occur on 

 the grooves of the epider- 

 mis over the vein.s. This 

 is plainly shown when a 

 harmless solution of con- 

 siderable strength is used ; 

 for after the evaporation 

 of the water the dry salt 

 is clearly seen. Some 

 plants, such as Primula 

 sinensis, have striations 

 radiating from the large 

 trichomes, which would 

 aid in conveying liquid 

 which happened to be 

 brought near the base, up 

 the trichome to a surface 

 less cutinized. (Fig. 5, st). 

 The leaf of Ampelopsis has peculiar striations (Fig. 11, H.S.), radiating 

 irregularly from the stomata. Striations are found on both sides of 

 the leaf over the veins. Decrock (An. Sc. Nat. 8, 13, i, p. 61, 1901) 

 noticed similar striations upon several plants of the Primulaceae. 

 Corrugations have been observed by Henslow and Stahl, though Stahl 

 assigned to them a far different function from that assigned by 

 Henslow. E. L. Gregory (1886) concluded from experiments 

 performed with many plants having hair coverings upon the leaves, 

 that the basal cells of the hairs were best fitted for the absorption 

 of water. 



An interesting instance of the absorption of salts by the leaves of 

 plants is given by Boehm (1875, P- 287), reviewed in Bot. Jahrsber, 

 f. 1875, s. 860. 



FIG. II. 

 A, epidermis, lower surface, showing striations ; B, 

 epidermis, upper surface ; C, section through epidermal 

 cells, lower surface ; D, upper surface, epidermal cells ; 

 E, epidermal cell, lower surface ; F, epidermal cell, upper 

 surface showing "pits": G, epidermal cell over vein; 

 H, section through leaf through one of the smaller veins ; 

 P, thin-walled parenchyma ; S, striations. 



