240 Transactions of the Canadian Institute. [Vol. VII. 



Both kinds of solutions, since they differ so little when in dilute form, 

 are designated in this paper, "in"; and the dilution is indicated by a 

 number written as the denominator of a fraction. 



Since so much seemed to depend upon the question of water- 

 absorption by leaves, a rather full discussion is entered into, more 

 particularly upon the literature pertaining to this subject, in order to 

 establish upon what grounds present views of plant physiologists are 

 based. Some experiments were made to test water-absorption directly, 

 but it was found that more light could be thrown upon the subject from 

 other sources. It was from the indirect side mainly that the question 

 was attacked, as it seemed, in the judgment of the writer, to be more 

 productive of fruitful results ; so the question of guttation drops, dew- 

 drops, and calcareous incrustations upon certain plants, was examined 

 in some detail with a view to learn something of their cause, chemical 

 nature and function. 



For the examination into the effects of solutions applied to the cut 

 ends of the petioles, leaves were selected which would readily show an 

 acid or an alkaline reaction, and which would live for a considerable 

 time in water without sending out roots. It was not so much to 

 determine how long leaves could endure the solution and live, as to 

 examine into the effects produced by the solutions so applied, and to 

 learn something of the cause of death. The same is true with regard to 

 the application of the solutions to leaf surfaces; and a comparison is 

 made of the effects of some of these upon Spirogyra, with that upon 

 leaves. 



On commencing the work of experimentation, and upon examining 

 into the literature pertaining to the subject, it was found that the 

 question first to be answered was in regard to whether living green 

 foliage leaves absorb water through the epidermis, or through the 

 stomata, in some way or other, from the surrounding medium, either as 

 liquid or as vapour. The popular notion is that water is so absorbed, 

 but the view expressed by many of the recent text-books on botany is 

 quite generally opposed to this. Some writers have "proved" experi- 

 mentally that water could be absorbed, while others apparently equally 

 reliable "proved" the opposite. This condition of affairs rendered it 

 necessary to examine the question in detail by careful and prolonged 

 experiment, and to study with considerable care, the literature which 

 pertains directly and indirectly to this subject. That water-absorption 

 is the very "corner-stone" of the problem is at once apparent, because 

 all the sojutions used are aqueous, and many of them are in very dilute 



