VARIOUS SUGGESTIONS. 135 



Mariotte, so well known by his researches into the com- 

 pressibility of air, represented the rise of the sap as de- 

 pendent upon what he called "the attraction taking place 

 in the narrow tubes" upon what, in fact, we now term 

 capillarity. "This first entrance of water into the roots is 

 in obedience," he said, "to a law of nature; for wherever 

 very narrow tubes exist which touch the water, it enters 

 into them, and even rises, contrary to its natural inclina- 

 tion." 



Many botanists adopted the opinion of Mariotte. But if 

 it were well founded, all capillary bodies, even inorganic 

 ones, ought to present a circulatory movement analogous 

 to that of the sap. Now, this is not the case. A body 

 must be animated, must be living, for attraction to take 

 place in the narrow tubes, and to produce a movement 

 comparable to that of the nutritive liquid. 



Malpighi attributed the rise of the sap to the alternating 

 rarefaction and condensation of this liquid by heat ; Perrault, 

 to a kind of fermentation ; De Saussure, to a peculiar irrita- 

 bility of the vessels. Of these three hypotheses, the first is 

 purely physical ; the second, chemical ; the third, vital. So, 

 as we see, there is something for everybody chacun d son 

 gout ! 



The same question has, in our own day, been taken up 

 from a new point of view, on the occasion of Dutrochet's 



