^iv. 



M. 



ifeaf, 



esfr 



% 



* 4 



i on 



eat 



dCi, 





■ -^ ^«// 



*. 





■ ^'^mks. 



;; 



^ how drl.u. 

 H: :v to pi/sn 



Wark 



f« 



7 



which ap- 



:ternal ele- 



of infet^s ; 



We ftall 



.etables are 



? 



iitials; ^ 



an 



Se^ 





la 



foi^ 



Sect. XIV 



OF PLANTS 



V7 



lefs th 



third of 



.111 ..A. th^^n bv more perfea animals, we (hall 

 lefs degree by vegetable buds, than oy mo ^ 



the fame idea to vegetable life ; and has ^^'^^^^''^tl^tZX 

 their irritability alfo originates from the o.ygen, -^ ^^ f ^ '^j;;^ 

 either by the refpiration of their leaves, or by the abfo> ption of the. 

 oot /nd indeed, as refpiration is every minute neceffary to an.mal 

 fe here is reafon to believe, that fomething .mrned.ate ly necefl^ry 

 to he exiftence of life is acquired by the lungs of an.mals from the 

 .tmofphere rather than from the food, wh.h they ^^ ^^^ 

 this, which is believed 



be the oxygen only 



bloo'd, and feparated again from it by the brain and fpinal marrow 



after having undergone fome change in the circulation or fecret.on of 



la the fame manner it is not improbable, but that the fpirit of 



it. 



may have a fimilar 



probably from the uncombined 



oxy-en of the air, refpired by the upper furfaces of their leaves; and 

 not from that, which is abforbed by their roots in a more combmed 

 ftate ; and that this oxygen is again feparated from therr juices by 

 the fenforium, or brain, of each individual bud. after having under- 

 gone fome change in the circulation or fecretion of it. See Seft. IV. 



I. 2. 



The circumftan 



ttending vegetable irritability 



fimilar to 



thofe belonging to the irritability of animals upon a lefs extenfive 

 fcale, as detailed in Zoonomia, Vol. I. Sed. Xll. 



When vegetable fibres have been long ftimulated more than na- 

 tural or ufual by increafe of heat, the fpirit of vegetation becomes ex- 

 haufted ; and in confequence a (lighter degree of cold will deftroy 

 them ; becaufe their fibres after having been long excited by a greater 



v^'hich is much 



lefs ; 



flimulus will ceafe to ad on the application of 



9 



4 



t 



