74 OF VEGETABLE SECT. XIII. 2. 



ing into wood forms the concentric circles, which we fee in 

 blocks of timber. 



The following circumftances evince the individuality of the 

 buds of trees. Firft, there are many trees, whofe whole internal 

 wood is periihed, and yet the branches are vegete and healthy. 

 Secondly, the fibres of the barks of trees are chiefly longitudinal, 

 refembling roots, as is beautifully feen in thofe prepared barks, 

 that were lately brought from Otaheite. Thirdly, in horizontal 

 wounds of the bark of trees, the fibres of the upper lip are al- 

 ways elongated downwards like roots, but thofe of the lower 

 lip do not approach to meet them. Fourthly, if you wrap wet 

 mofs around any joint of a vine, or cover it with moift earth, 

 roots will (hoot out from it. Fifthly, by the inoculation or in- 

 grafting of trees many fruits are produced from one ftem. 

 Sixthly, a new tree is produced from a branch plucked from 

 an old one, and let in the ground. Whence it appears that the 

 buds cf deciduous trees are fo many annual plants, that the 

 bark is a contexture of the caudexes of each individual bud ; 

 which confifts of a leaf or plumula at top, of a radicle below, 

 and of a caudex, which joins thefe together, and conftitutes the 

 bark of the tree, and that the internal wood is of no other ufe 

 but to funport them in the air, and that thus they refemble the 

 animal world in their individuality. 



The irritability of plants, like that of animals, appears liable 

 to be increafed or decreafed by habit ; for thofe trees or fhrubs, 

 which are brought from a colder climate to a warmer, put out 

 their leaves and bloflbms a fortnight fooner than the indigenous 

 ones. 



ProfeiTor Kalm, in his Travels in New York, obferves that 

 the apple-trees brought from England bloflbm a fortnight foon- 

 er than the native ones. In our country the fhrubs, that are 

 brought a degree or two from the north, are obferved to flur- 

 ifh better than thofe which come from the fouth. The Sibe- 

 rian barley and cabbage are faid to grow larger in this climate 

 than the fnnilar more fouthern vegetables. And our hoards of 

 roots, as of potatoes and onions, germinate with lefs heat in 

 fpring after they have been accuflomed to the winter's cold, 

 than in autumn after the lummer's heat. 



II The ftamens and piftils of flowers (hew evident marks of 

 fenfibility, not only from many of the flamens and fome piftils 

 approaching towards each other at the feafon of impregnation, 

 but from many of them clofing their petals and calyxes during 

 the cold parts 'of the day For this cannot be afcribed to irri- 

 tation, becaufe cold means a defect of the itimulus of heat ; 

 but as the want of accuttomed ilimuli produces pain, as in cold- 



nefs, 



