252 The Rev. Mr. Keith on the (APRIL, 
Articie II. 
On the Hypothesis of Mr. Knight, accounting fer the Direction 
of the-Radicle and Germen. By the Rey. Patrick Keith. 
(To Dr. Thomson.) 
SIR, Bethersden Vicarage, Kent, Jan. 29) 1819. 
{n your number for April, 1817, you have given an account 
of the proceedings of the Linnean Society of London, by which 
it appears that, on Tuesday, March 4, preceding, a paper, by 
T. A. Knight, Esq. was read to the Society, containing a defence 
of what is called my attack upon his hypothesis, of which I 
etry exhibited an inaccurate representation. This 
inaccuracy | have since admitted and apologized for in the proper 
quarter, but not to the prejudice of any future inquiry. If Mr. 
Knight’s hypothesis is founded in truth, it will suffer nothing 
from my investigation ; and if it is founded in error, the sooner 
the error is detected the better. On this account, I have given 
it a second perusal, and I am desirous of communicating the 
result of it to the public through the medium of your Annals. 
But that I may not again exhibit an incorrect view of Mr. 
Knight’s hypothesis, I will give it in his own words, as it occurs 
in an inference drawn from the two following experiments. 
_ Exper, 1.—On the circumference of a vertical wheel perform- 
ing 150 revolutions in a minute, by which the influence of 
gravitation was conceived to be wholly suspended, beans were 
placed im all directions. The result was, that the radicles 
uniformly turned their points outwards from the circumference of 
the wheel; and in their subsequent growth receded nearly at 
right angles from its axis. The germens, on the contrary, took 
the opposite direction ; and in a few days their points all met in 
the centre of the wheel. They even extended beyond it; but 
the same cause which first occasioned them to approach its axis 
still operating, their points returned, and met again at the 
centre.* 
Exper. 11.—In consequence of some slight objections which 
Mr. Knight anticipated as likely to be alleged against the con- 
clusion he was inclined to draw from the foregoing experiment, 
a second experiment was instituted, by adding to the former 
machinery a horizontal wheel, which was made to perform 250 
revolutions in a minute, and to the circumference of which, 
beans were fastened as before. The issue was, that the radicles 
were protruded outwards and downwards, about 10° below, and 
the germens inwards and upwards, about 10° above the plane of 
the wheel. But when the rapidity of the wheel’s motion was 
diminished, the radicles were more perpendicular, and the ger- 
* Phil. Trans. 1806. Part I. p. 100, 101. 
