144 Vegetable Staticks. 



If the fap circulated, it muft needs have 

 been feen defcending from the upper pare 

 of large gafhes cut in branches fet in wa- 

 ter, and with columns of water preffing on 

 their bottoms in long glafs tubes, in Ex- 

 periment 43, and 44. In both which 

 cafes, it is certain that great quantities of 

 water paffed thro' the ftem, fo that it muft 

 needs have been feen defcending, if the return 

 of the fap downwards were by trufion or pul- 

 fion, whereby the blood in animals is re- 

 turned thro* the veins to the heart : And 

 that pulfion, if there were any, muft necef- 

 farily be exerted with prodigious force, to 

 be able to drive the fap thro' the finer capil- 

 laries. So that, if there be a return of the 

 fap downwards, it muft be by attraction, 

 and that a very powerful one, as we may 

 fee by many of thefe experiments, and par- 

 ticularly by Experiment 11. But it is hard 

 to conceive, what and where that power is, 

 which can be equivalent to that provifion 

 nature has made for the afcent of the fap 

 in confequence of the great perfpiration of 

 the leaves. 



The inftances of the Jeffamine tree, and 

 of the Pafilon tree, have been looked upon 

 as ftrong proofs of the circulation of the 



fap, 



