256 The Rev. Mr. Keith on the fAPRIL, 
+d of an inch from the first ; the third at the distance of about 
4d ofan inch from the second ; and the fourth nearly as before. 
On the 9th, the radicle was 1} inchin length, the three marks 
next the base being nearly as before, and the mark next the 
apex being the only one that was carried down. 
On the 10th, and as long as any further observations were 
made, it was still the lower extremity of the radicle, and that 
only, which was carried down. But enough had been previously 
observed to show that the assumed peculiarity of the elongation 
of the radicle is founded in a mistake ; and that the root in its 
incipient state, like the stem in és incipient state, is augmented 
by the mtrosusception and deposition of additional particles 
throughout its whole mass ; or “‘ by a general extension of parts 
already formed;” though it may afterwards, like the stem, 
become so firm and compact as no longer to admit of augmenta- 
tion in that way. I suspect, therefore, that Du Hamel’s experi- 
ment was not instituted at a sufficiently early period of the 
radicle’s or root’s growth; or that it was somehow or other 
unnaturally affected by being placed in water; or that there are 
exceptions to the rule, which my experiment establishes. 
The bean, which was the subject of the above experiment, 
grew, as has already been stated, in garden mould, and was 
taken up and planted again at every observation. My observa- 
tions were not, however, confined to that single bean; they 
were extended to many others, as well as to the radicles of mus- 
tard, cress, and radish seed, all which gave similar results ; so 
that if there are any exceptions to the rule which my experiment 
establishes, the radicle of the bean, on which Mr. Knight’s two 
experiments were made, is not one of them. 
hus it is proved that the facility with which the germinating 
radicle might be influenced by the agency of gravitation from the 
supposed peculiarity of its mode of growth is wholly imaginary ; 
and if it were even the fact, still the particles by which it is 
augmented, though originally fluid, or changing from the fluid 
to the solid state, are contained within an epidermis which 
bounds and confines them, and are not committed to the 
influence of gravitation merely, like the trickling drops of water 
that are added to the point or surface of an icicle. 
If any other evidence were wanted to prove the fact that the 
root is augmented by the introsusception and deposition of addi- 
tional particles throughout its whole extent, I would adduce the 
case of the garden radish when past the stage of germination. 
In taking up young radishes that are just fit for the table, it is 
no uncommon thing to meet with an individual that is elevated 
at the collar by at least an inch above the surface of the soil. 
But how is this elevation to be accounted for except upon the 
principle now assumed ? It must not be said that the base of the 
root has been pushed upwards, because the apex could not get 
downwards ; for the apex has been descending all the while, and 
if 
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