Sect. XIII. 3. ANIMATION. 75 



nefs, hunger, and thirft of animals, thefe motions of vegetables 

 in clofing up their flowers mult be afcribed to the difagreeable 

 fenfation, and not to the irritation of cold. Others cioie up 

 their leaves during darknefs, which, like the former, cannot be 

 owing to irritation, as the irritating material is withdrawn. 



It may be objected, that, when the petals and calyxes of flow- 

 ers, and the leaves of fome vegetables, clofe in the night, this 

 may be their natural (late, like the clofing of the eyelids in the 

 fleep of animals ; and that it mould thence be afcribed to the 

 fufpenfion of volition, rather than to difagreeable fenfation. 

 It may be anfwered, that in the fleep of animals the clofing of 

 the eyelids may not be the natural (late of the part, fince in the 

 great inirritability and infenfibility attending fome fevers the pa- 

 tients ileep with their eyes half-open, and in actual death the 

 eyes do not clofe fpontaneoufly, and that hence the clofing cf 

 the eyelids in fleep feems to be in confequence of our increafed 

 internal fenfibility to light, or duft, or drynefs. 



And it is certain, that the ab fence of the accuftomed quanti- 

 ty of heat decreafes the action of animal fibres, as is evinced by 

 the palenefs of the fkin, when it is expofed to great cold ; and 

 the increafed action of the fubcutaneous mufcles,as in fhudder- 

 ing from cold, is certainly owing to the difagreeable fenfation 

 confequent to the diminution of the accuftomed irritative mo- 

 tions, as in Sect. XXXII. 10; and Sect. IV. 5. 



An excefs of moifture on fome parts of flowers and leaves 

 may occafion a difagreeable fenfation, as when a drop of water 

 gets down the windpipe into the lungs of animals, and may 

 thus occafion them to clofe. 



The approach of the anthers in many flowers to the ftigmas, 

 and of the piftils of fome flowers to the anthers, mud be afcri- 

 bed to the paflion of love, and hence belongs to fenfation, not to 

 irritation. 



III. That the vegetable world pofTefTes fome degree of vol- 

 untary powers, appears from their neceffity to fleep, which we 

 have (hewn in Seel:. XVIII. to confift in the temporary abolition 

 of voluntary power. This voluntary power feems to be exerted 

 in the circular movement of the tendrils of vines, and other 

 climbing vegetables ; or in the efforts to turn the upper furface 

 of their leaves, or their flowers to the light. 



IV. The aflbciations of fibrous motions are obfervable in the 

 vegetable world, as well as in the animal. The diviiions of the 

 leaves of the fenfitive plant have been accuftomed to contract at 

 the fame time from the abfence of light ; hence if by any other 

 circumftance, as a flight ftroke or injury, one divifion is irrita- 

 ted into contraction, the neighbouring ones contract alfo, from 



their 



