251 
Of the Pith of Roots. 
of a root therefore confifts of vefieis and fibres, and pro¬ 
bably thefe fibres themfelves are tubular. 
If you take the roots of vine, fennel, dandelion, plumb- 
tree, elder, willow, &c. and lay them for fometime to dry, 
then cut off a thin fiice of each tranfverfly, and place it 
before the microfcope, by pinching one edge thereof be¬ 
tween the nippers, the light will then be trajedled through 
the perforations of all the vefieis both great and fmall, they 
are fcarce ever vifible in the frefh dices of thefe roots. 
A clear and elegant fight of the fibres which compofe 
the air vefieis, may be obtained by fplitting a vine root, 
or a piece of oak, and may be feen in the fide of the 
greater air vefieis, in the refemblance of needle-work; 
the fpiration of the fibres may be better obferved in the 
trunk than in the root, and befi in young plants, but not 
fo well by cutting as fplitting, or by tearing off fome 
fmall piece, through which they run; their confirmation 
being by this means not fpoiled. 
But in the leaves or tender ftalks of all fuch plants as 
fhew upon breaking a kind of down or wool, they may 
be feen drawn out, and that fometimes to the naked eye. 
This wool being nothing elfe but a certain number of 
fibres drawn out of their fpirai pofition, appearing more 
or lefs in the leaves and other parts of moft plants, as in 
the vine, fcabious, &c. in the feales of a fquil they are fo 
eafily feparable, as to fhew the plate or zone into which the 
air vefieis are ufually refolved, which is nGt one fingle 
piece, but made up of feveral round fibres, running pa¬ 
rallel, and knit together by other fmaller ones tranfverfly 
in the form of a zone. 
Of 
