5H 



PRODUCTION OF Sect. XVIII. 2. 13. 



are felled, are annually produced ; and are faid generally to be thicke 



on 



th 



fide of the trunk, which grows towards the fouth, th 



\ 



the northern fide, and thicker in the fummers moft favourabl 



\ 



getation than th 



trary 



Thefe rings, as they lofe th 



ble life, and at the faoie time a part of their moifture by evapora 

 Dn, or abforption, gradually become harder and of a darker colour 

 fomuch, that by counting their number, it is faid, th 



but that the mildnefs or moifl 



of each fu 



the age of the tree, 



mer during the time of its growth may be eftimated by the refp 



thicknefs of the rings of timber 



3 



In the fame manner the central pith alfo lofes its vegetabi 



fe, probably after the firft yea 



and th 



o 



radually becomes ab 



forbed, or fo impregnated with ligneous particles, as not to be diftin- 

 guifhed from the furrounding wood. The pith of a young bud fo 



I 



refembles the brain and fpinal marrow of anim 



in 



fpe6t to its 



central fituation, that it probably 



out nerves to every 



o 



fibre of the bud ; though thefe have yet efcaped our eyes and glafles 

 and thus furnifhes the power of motion, 

 the various parts of the vegetable fyftem. 



of fen fat 



to 



One curious fa6t, which 



I h 



obferved, feems to 



this conie<St 



which 



% 



that the pith of a laft yearns twig communicates to the leaves on each, 

 fide of it, but not to the new buds in the bofoms of thofe leaves ; be- 

 caufe thofe new buds are each an individual being, generated by the 

 caudex of the leaf, and muft therefore pofTefs a fenforium of its own. 

 See Se<fl. I. 8. and IX. 2. 4. 



The pith of trees contains much mucilage, as well as the flalks 

 of annual and perennial plants, whether they are hollow or not ; the 

 pith of a palm-tree, cycas circinalis, is foftened with water, and 



f 



pafled through fieves. 



and thus forms the fagoe 



of our (hops ; it is 



!►- It "fl 



poffible the large pith of the flalks of artichokes, cinara fcolymus, 

 mif^ht be manufactured into a fimilar kind of taftelefs mucilage ; and 

 |he pith of the young fhoots of elder, fambucus nigra, might alfo. 



poffiblj^ 





• -4 



