« 



4. 



^ 



J 



X^ 



^ * 





• • 



4. 



V 



■"• 



f &^ 



y othe 



r 



u 



y; and 

 e fcJl 



wppofe, 



i gilled 



b''oken 

 ni, and 



:.za au- 



Dj..te: 



- ' " 



m con 



I f 



-^r- 



- r*rs 



T^ 



i 



-:ght 



c! efo m e 



h:ir dii^ 



bef 



f>o 



r- -'>;oa 



a 



boil 



t-^'S 



(f 



> 



» 



do " 







Sect. XVII. 3. i. 



ROOTS AND BARKS 



491 



of common fpotted arum, and of arum arlffarum to be boiled, and on 

 taftlno- them found my tongue and lips almofl: excoriated. The na- 

 ture of this kind of acrimony has not been fufficiently inveftigated 

 by the chemifts, but probably depends on a fixed eflential oil. 



I. 



III. Barks. 



r 



The barks of the trunks of trees are fimilar to thofe of their 



d may be efteemed a part of them, as they confiH: of an 

 e of the vellels, which defcend from the plume of each 



dividual bud 



the radicle of 



d 



ft 



Its 



dex 



Th 



e 



\ 



r 



bark neverthelefs of the root is furni(hed with lymphatics to abforb 



water and 

 moifter cu 



phatics to 



J 



from th 



th, and is covered with a 



hile the bark of the ftem is furnifhed with lym 



abforb 



fture from th 



d 



ered with a d 



cuticle ; the latter refembling the external fkin of anima 

 lymphatics, which open i 



d the 



po 



it; 



d th 



e former refembling th 

 mucous membrane of the ftomach, and its la(Sleals. 



As the fap -juice rifes in all deciduous trees 



during 



o 



the vernal 



months to expand their foliage, though probably in greater quantity 

 in fome trees than in others, it muft confift not only of fugar and 

 mucilage, as in the nnaple and birch, but of various other ingredi- 

 ents in different trees, which have not been attended to; as appears 

 from the tafte of their young leaves, as of oak or afh. And as fome 

 of thefe materials refide in the roots and fap-wood or alburnum, fo 

 others of them may perhaps refide in the bark, where they have been 

 depofited during the preceding fummer, and become lignified by the 

 warmth of the fpring, or diflblved by the moifture abforbed from 



the earth and air, and conveyed upwards to the opening buds; 

 whence it is evident, that the barks of trees fliould be taken off for 

 ufe in winter or in early fpring, before their buds begin to expand ; 

 as then a part of thefe nutritious juices, or of the other materials, 

 which are required for medicines, or in the arts of dying and tan- 



3R2 



ning, 



