Of the Roots of Plants. 241 
The fame principle brings the feed into its due fitua- 
tion at firft; in a bean planted upfide down, the plume 
and radicle are eafily perceived with the naked eye, to 
Ihoot at firft directly for about an inch ; but thenceforward 
they begin to bend, the one downwards, and the other 
upwards, as in the example of the orange feed, fig. 457 ; 
the like is feen in a heap of barley to be made malt, in a 
quantity of acorns laid to fprout in a moift place, &c. 
each grain of barley in the firft cafe, and each acorn in the 
fecond, hath a different fituation, and yet all the fprouts 
tend dire&Iy upwards, and the roots downwards, and the 
curvity or bend they make, is greater or lefs as their fitua¬ 
tion approaches more or lefs to the direction wherein no 
curviture at all would be neceffary. Nov/ two fuch op- 
pofite motions cannot arife without fuppofing fome confi- 
derable difference between the two parts; the only one 
we know of, is, that the plume is fed by a juice, imported 
to it by tubes parallel to its fides; whereas the radicle 
imbibes its nouriftiment at all the pores in its furface. As 
oft therefore as the plume is either parallel or inclined to 
the horizon, the nutritious juice, feeding the lower parts 
more than the upper, will determine its extremes to turn 
upwards, for the reafon already affigned. On the con¬ 
trary, when the radicle is in the like fituation, the nutri¬ 
tious juice penetrating more copioufiy through the upper 
part than the under, there will be a greater accretion of 
the former than the latter; and confequently the radicle 
will be bent downwards ; and this mutual curvity of the 
plume and radicle muft continue, till fuch time as their 
fides are nourilhed alike, which cannot be till they are 
perpendicular f . 
Roots are generally diftinguifhed by their figures, fome 
being entire, as liquorice ; parted, as faint johnwort; fome 
R parted 
£ Men, d< 1 , Acad. Roy, des ciences, No. 1708. 
