C 218 3 



the living action of the vessels, for they cannot have 

 been more than full; and their diameter is so small, 

 that if it were to continue unaltered, the capillary at- 

 traction would be more than sufficient to contain their 

 contents, and consequently not a drop would flow out. 

 Since therefore the liquid escapes, it must be driven 

 out by a force different from a common physical force* 



To this reasoning it may be answered, that the 

 sides of alUhe vessels are soft, and capable of collaps- 

 ing by gravitation, as veins do in animal systems long 

 after they have lost all their vitality; which is an effect 

 totally different from vital or irritable action; and the 

 phenomenon may be compared to that of puncturing 

 a vessel of elastic gum filled with fluid, both above and 

 below; the fluid will make its way through the a- 

 pertures, though in much larger quantity from the 

 lowest, which I have found is likewise the case with the 

 Spurge. 



Dr. Barton has stated, that plants grow more vi- 

 gorously in water in which a little camphor has been 

 infused. This has been brought forward as a fact in 

 favour of the irritability of the vegetable tubular sys- 

 tem. It is said that camphor can only be conceived 

 to act as a stimulus, by increasing the living powers 

 of the vessels, and causing them to contract with more 

 energy. But this kind of speculation is very unsatis- 

 factory. Camphor, we know, has a disagreeable pun- 

 gent taste, and powerful smell; but physicians are far 

 from being agreed whether it is a stimulant or sedative, 

 even in its operation upon the human body. We 

 should have no right whatever, even supposing the ir- 



