4. 



I the 



bee 



of 





as 



ths 



r 



into 



e 



lling: 



•ther 

 wth 



;rba- 

 tur- 

 ,s In 



and 

 ncd 



? 



ifle 



)rin 

 the 



►vby 



eive 

 ac- 



ting 

 the 



son 

 the 



day 



Sect. III. 11. 4 



UMBILICAL VESSELS 



29 



day and night. In regard to capillary attraflion, however high it may 

 raife a fluid in very foiall tubes, it can not make it flow over them, 

 as the fap-juice did in Dr. Hales's vine-ftump ; nor can it raife a fluid 

 quite to a level with the upper rim of a glafs tube, as the fluid is there 

 more attra6ted downwards by the glafs befides its gravity, and is left 

 in confequence with a concave furface. 



The means by which vegetable abforbent veflels in their living 



ftate imbibe the fluids of the earth and atmofph 



d carry them 



forwards with fo much for 



mufl be fimilar to thofe, with which 



mal abforbent veflels perform th 



fam 



e 



ffice 



th 



is by th 





mouths being excited intoadion by the ftimulus of the fluids, which 



they abforb. - 

 This circumfl 



firmed by the evident proofs of th 



tability of plants in various other inftances, as the clofing and open- 



Ino- of the petals and calyxes of flowers by light and darknefs, warmth 



ire, and by the motions of the leaves of 



and cold, drynefs and moifl: 



mimofa, or fenfit 



plan 



and of dionoea mufcipula, by^any me 



chanical ftimulus. To this might be added a variety of inftances of 

 the irritability of vegetables to the ftimulus of heat, being increafed 

 after a previous expofure to cold, exadly in the fame manner as hap- 

 pens to animal bodies, which are enumerated in a note in the Botanic 

 Garden, Vol. I. Canto I. 1. 322, whence the reciprocal times of the 

 aflino; and the cealing; toad of thefe vernal vegetable abforbents, which 



in the experiments both of Dr. 



to 



are 



h 



termed umbilical veflels 



Hales and Dr.Walker, may be readily explained by their having been 



or excited into adion by the warmth of the 



benumbed bv the cold 



air or 



I 



th. See Sea. XIII. 2. 3 

 one experiment neverth( 



fs of Dr. Walker's thefe vefl"els 



fionally aft as capillary fyphons, becaufe when he bent d 



branch much lower than its origin from the tree, and cut off the end 



of 



in the bleeding feafon 



i 



the fap flowed from th 



ty of 



this branch fo bent dow 



fome wounds two or three feet 



/ 



lower 



