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



showed by experiments that living foh'age leaves could absorb water 

 both as rain and as dew. His work was important, and he has been 

 quoted by many, especially by the earlier writers, possibly in part 

 because of his careful and close reasoning coupled with his rather 

 unique experiments. After Mariotte the records of work done in this 

 connection are fragmentary and scattered, and it was not till about fifty 

 years later, when the experiments of Stephen Hales (1726, p. 56) were 

 published, that a new impetus was given to the subject. In 1753 

 Bonnet (1754, p. 26) made some important investigations relative to 

 water absorption and came to the same general conclusions as did 

 Mariotte and Hales, namely, that water was absorbed by leaves with 

 evident advantage to plants, and that water-absorption was a normal 

 function of leaves. Senebier in his text (1806, 3, p. 94) refers to the 

 works of Bonnet and Hales, and, after reviewing some of their experi- 

 ments, concludes that water is aborbed. In the work of Dutrochet 

 (1837, p. 328), one finds the idea that water is absorbed somewhat 

 extended, and as Dutrochet puts it — "Physiologistes ont considere les 

 feuilles comme des sortes de racine aeriennes destinees a puiser dans 

 I'atmosphere I'eau et les autres principes qui contribuent a la nutrition 

 du vegetal." This view seems rather too strong on the side of 

 water-absorption when one examines the works of the earlier writers 

 whom he quotes, and upon whose works he very largely bases his 

 statements. 



All the works just mentioned are now looked upon as classic, and 

 the names will be remembered as long as plant physiology is deemed a 

 subject worthy of investigation. These works form a sort of epoch, not 

 only in matter of time, but also in views and conclusions ; and one 

 is struck by the singular similarity in aims and argument among those 

 authors. 



In the botanical works of Treviranus (Vol. I., 1835), we find that the 

 views upon the question are opposed in part to that of the authors just 

 mentioned, especially to that of Bonnet and Hales ; and his work 

 introduces a side of the question which has stood its ground up to the 

 present time. That a function of foliage leaves was to absorb water 

 and dew, had up to this time been looked upon as established, not so 

 much because of the works and views of Mariotte, Hales, Bonnet, 

 Senebier and Dutrochet were accepted as proving so much, but rather 

 because the view was according to the popular notion and seemed self- 

 evident. The experiments of Treviranus, and of others of less note, 

 about the same time, raised some startling questions in regard to the 



