5 



ayb 



e 



^^ 



at 



^Jths 



) 



^ and 

 •ough 



. f< 



ea 



^lefs 



a 



fea- 



tin 



a 



ere IS 

 :ar to 

 tof 



a 



e 



Isth 

 forth 



I 



vein, 

 ches, 



eries 



) 



\ 



s foil. 



m, or 

 rhaps 



com- 



e, are 



a tree 



/ou 



m 



uch 



It was 



/n 



-nal 



rie^ 



/ 



Sect.III. II. 6. 



UMBILICAL VESSELS. 



31 



ried upwards probably by the annular contraction of the fpiral fibres^ 

 which I believe compofe thefe abforbent vefTels, in fuch quantities as 

 to bleed wherever the alburnum is expofed or wounded, yet that af- 

 terwards the exhalation by the numerous leaves becomes fo great, 

 that the adions of the new radical and lateral abforbents do not 



r 



r 



fupply a fluid fo faft, as it could otherwife be expended in the growth 

 of the plant, or diffipated into the air ; and as the velTels, which pafs 

 down the trunks of trees, inofculate in variety of places, as is feeii in 

 the cloth made at Otaheite from the bark, of a mulberry-tree, when 

 a wound is made through fome of thefe veffels, the fluid, which 

 might otherwife ooze out, is carried away laterally by thofe in their 

 vicinity; and as the veflTels of vegetables are rigid, and do not collapfe 

 when wounded like thofe of animals ; and as the circulation in them 

 is comparatively flow, but little of their contained fluids are poured 

 out of them when wounded in the fummer months. 



6. From all thefe obfervations it finally appears, that the umbilical 

 veflTels of each bud are fimilar to thofe of a feed, which are called by 



umbilical cords, which. 

 , and of potatoes under 



I 



Dr. Grew femina 



d th 



ke th 



e 



form the wires of ftrawberries above ground 



ground, they fupply the new vegetable with nutriment, till the leaves 

 are expanded in the air, and new roots are pufhed out and penetrate 

 the earth. - 



There is alfo a curious analogy between thefe umbilical veffels of 

 buds, which exift in the alburnum of trees, and thofe belonc^ino- to the 



hick 



th 



which confifts In their both poflTefli 



&^"to 



veflels ; thofe of trees pafs horizontally from the bark to the alb 

 num, and that of the egg exifls at the broad end of it. 



Th 



prob 



that the fluid in the fine extremities of the nev/ veffels of 



the embryon bud becomes oxygenated by thefe horizontal air-veffel 

 in the fame manner as the fluid in the terminations of the arteries c 

 the chorion of the chick is believed to become oxygenated- by the a 



\ 



ined 



i 



