Of the hFood of ‘Trees. 267 
fig. 512. which reprefents part of one of the aforefaid 
air veiTels feen length-wile, and as it appeared before the 
magnifier. 
The fecond fort of perpendicular vefTels which tend 
upwards, are feen at e e, fig. 508. and are alfo compofed 
of exceeding fine fkins x , in which are feen fome fpots 
that in the microfcope appear like globules, as at O N, 
fig. 511. which fhews one of thefe fecond fort of vefTels 
cut lengthwife. 
The third fort of thefe vefTels which run upwards, are 
extremely fmall and in great abundance, as appears 
throughout the whole fpace H I K L, fig. 508. Thefe 
alfo are compofed of extremely fine fkins ; they are feen 
length-ways between P Q, fig. 511. 
G G G, fig. 508. are another fort of vefTels, whicli 
run horizontally from the bark to the pith: thefe feemed 
to extend themfelves in furrows, and were crooked or 
bowed round the knots. When the wood is cut length- 
wife, thefe horizontal vefTels are cut acrofs, as at G G G, 
fig. 511. The fecond fort of horizontal vefTels are greatly 
numerous, which when the oak is cut length-wife, are 
alfo cut acrofs, and appear to the naked eye as fig. 513. 
Fig. 496. fhews a piece of elm cut tranfverfly as it ap¬ 
peared to the naked eye; and fig. 497. a microfcopic 
pidture of the fame. A B, CD is the breadth of the 
ring the tree had increafed in one year. The fmaller 
perpendicular vefTels are fituate between and joined to the 
larger, having fmaller ones between them, as in oak; 
the tubes here alfo are compofed of fkinny membranes* 
A C and B D, fig. 497. are horizontal vefTels feen length- 
wife. Fig. 498. is an upright fedfion of the wood of elm 
jnagnified, in which G G fhews the exceeding fmall 
vefTels 
Leeuwenhoek’s Anat. & Contemp, Vol. I. p. 3. 
