/ 



".6. 



•II. 



4. 



rfro 



U) 



otUs 



•al vef. 



utum 







11 



mors of 



- bark, 

 "il vef, 

 nt like 

 iment/ 



velTels, " 

 ) Inter- 



h con- 



lOtS, fo 



bud, or 

 fimilar 

 impro* 

 Jen, as 



. Sea. 







. riling 

 indth 

 birch 

 rds the 



e 



le 



tree 



.tcb, 



or 



k 



the 



trce> 



Sect. III. II. 7 



UMBILICAL VESSELS 



3 



tree, by flopping up their fpiracula ; and why covering an egg with 

 creafe or varnifh is faid to prevent the produdion of a chicke 



the broad end of 



ew bud 



preventing a change of air at 



7. We may conclude that the umbihcal vefTels of 

 formed alono- with a refervoir of nutritious ahment about midfummer 

 in the bark, which conftitutes the long caudex of the parent bud, in 

 the fame manner as a refervoir of nutritious matter 





broad caudex of th 



formed in th 



p or onion, for the nourifhment of 



the rifing ftem 



And that thefe 



bil 



effels of th 



em 



bryon bud, and the refervoir of nutriment laid up for it, which is 

 fecreted by the glands of the parent bud, and now intermixed with 

 the prefent bark of th 



become gradually changed into albur 



m 



or fap-wood 



the feafon ad 



part even before the 



end of fummer, and entirely during the winter months. 



That the'alburnum of trees, which exifts beneath the bark both of 

 the trunk and roots of them, contains the nutritious matter depofited 

 by the mature leaves or parent buds for the ufe of the embryon buds, 

 appears not only from the faccharine liquor, which oozes from the 

 wounds made in the vernal months through the bark into the albur- 



betul 



but alfo from the fol 



duded in th 



before the 



num of the birch and maple, 

 lowing experiment, which w 



vernal fap-juice rifes. 



Part of a branch of an oak-tree in January was cut off, and divided 



fully into th 



parts 



th 



bark, the alburnum 



d the heart 



Thefe were fhaved or rafped, and feparately boiled for a time in wa 



ter, and then fet 



warm room to ferment ; and it was feen that 



the decodion of the alburnum or fap-wood pafled into rapid ferm< 



d became at length acetous, but not either of the oth 



er 



tation, ai 



which evinces the exiftence both of fugar and mucilage in the albur- 

 num durincr the winter months ; fince a modern French chemift has 

 Ihewn by experiments, that fugar alone will not pafs into the vinous 

 fermentation, but that a mixture of mucilage is alfo required; and 



F 



from 



