32 UMBILICAL VESSELS. Sect. III. 11.6, 



contained at the broad end of the egg, as alluded to in Sed. II. 4. 



and III 



4 



/* 



A circumftance, in which the bud niay be conceived to differ from 

 the eo-CT, confifls in the feparation of the egg from its parent, as foon as 

 the fetus has acquired a certain maturity, along with its umbilical vef- 

 fels, and its refervoir of nutriment. But in vegetables fomething 

 fimilar occurs, for the parent bud is feparated by death in the autumn 



I : the leaf falls off, which was the liines of 



from its embryon offspring ; 

 the parent bud, and the vefTels of its caudex, which formed the bark, 

 coalefce into alburnum, or fap-wood, furrounding the umbilical vef- 

 fels of the new bud ; which thus may be faid to loofe its parent like 

 the egg:, but retains its umbilical veflels, and a refervoir of nutriment, 



\ 



which exifts in the fap-wood, and alfo another fyflem 

 which conftitute the new bark of the tree, cor 



f 



(Tels 



liftinsf of th 



woven caudexes of each individual new bud. 



But as the umbilical veflels of plants above defcribed, which con- 

 flitute the alburnum of the trunks of trees, and the feminal roots, fo 

 called, of the growing feed, convey nutriment to the embryon bud 

 to the rifing plumula, as well as oxygenation, they 



not fi 



that refped to the placenta of the animal fetus, and were impro 



Card 



as 



perly called placental veffels in the notes to the Botanic 

 the placenta of the animal fetus is (hewn in Zoonomia, Vol. I. Se£l. 

 XXXVIIJ. to be an organ of refpiration only, like the gills of fifh, 

 and not an organ for nutritiop. 



Hence when the cotyledons of feeds are cut away from the rifing 

 plume, the plant becomes a dwarf for want of nutriment ; and the 

 wounding or expofmg the alburnum of bleeding trees, as of the birch 



or 



mapl 



the vernal month 



obtain the fap-juice retards th 



expanfion of the new buds, and the confequent growth of the tree. 

 Hence alfo it appears, why fmearing the bark of a tree with pitch, or 

 oil, or paint, is liable to deftroy the new buds, and confequently the 



5 



tree, 



■ 



i 



s 



I 



