266 The Rev. Mr. Keith on the [AprrE, 
the radicle began to pomt downwards, and the extremity of the 
germen to point upwards.* 
~ Another objection arises from the fact that few branches grow 
perpendicularly upwards ; and that roots always spread horizon- 
tally. To this, Mr. Knight replies, that the luxuriant shoots of 
trees that aboundin sap do almost uniformly turn upwards, though 
the more feeble and slender shoots of the same trees grow in 
almost every direction, probably because their fibres being more 
dry, and their vessels less amply supplied with sap, they are less 
affected by gravitation.+ If Mr. Knight’s hypothesis is insuffi- 
cient to account for the direction of the stem, it will be also 
insufficient to account for the direction of the branches. But it 
may be observed, that a great flow of sap is not at all necessary 
to uprightness of growth. 
On June 1, 1818, a shoot ofa raspberry, of about 20 inches in 
length, was found to have been broken across, near the base, by 
a violent gust of wind, and separated entirely from the root, 
except by a small portion of bark, of about a quarter of an inch 
m breadth. It was lying flat upon the ground by the whole of 
its length, but was beginning to ascend by the summit. 
On the 8th, the vertical portion at the summit was three 
inches in length. 
On the 15th, the vertical portion at the summit was six 
inches in length. Thus, there was a rapid and upright increase 
of the shoot, and yet there could not possibly have been a great 
flow of sap. 
Mr. Knight regards the numerous lateral roots that issue from. 
the primary radicle as assuming a horizontal direction, because 
they are much less succulent than the primary radicle, and con- 
sequently less obedient to gravitation ; and because they meet 
with less resistance from the superficial soil than from: the soil 
below; so that the first and perpendicular root, having executed 
its office of securing moisture to the plant whilst young, is thus 
deprived ofits proper nutriment, and ceases almost wholly to grow. 
o this it may be teplied, that when the seed is made to ger- 
minate in the open air, the lateral shoots issuing from the primary 
radicle are still horizontal, or nearly so, though the primary 
radicle itself is not always perpendicular. Of three radicles 
protruded from three beans germinating at rest, in the dark, and 
in the open air, by being tied to a small slip of wood placed 
across an earthen pan at the distance of three inches from the 
bottom, the first receded gradually from the perpendicular till at 
about the length of two inches it formed an angle of 40°. The 
second, at the same length, formed an angle of 45°; and the 
third, at about the length of one inch, was horizontal by the 
lower half. What more could have been expected from a hori- 
* Phil. Traus. 1806, Part I. p. 106, + Ibid. { Ibid. 107, 
