492 The Rev. P. Keith on the Conditions of Germination, 
Mr. Keith. He would have seen also that radish-seed, which 
M. Lefébure could not prevail upon to germinate till it was 
quite ripe, will germinate, when it pleases to do so, before 
that period arrives. If left long upon the stalk in a wet sea- 
son it will germinate even in the pod. Also Jemon-seed will 
sometimes germinate in the very centre of its pulpy pericarp 
even before the fruit is cut open. 
After all, we regard these apparent exceptions as amounting 
absolutely to nothing. The seeds were not ripe, it is true, in 
the common acceptation of the term, which supposes them to 
be as dry and as hard as a bone; but they were ripe in the 
physiological acceptation of it, and that is enough. ‘The seed 
that will germinate is, physiologically speaking, ripe; that is, 
its fluids have been so elaborated in the process of its matura- 
tion, and its solids so vitalized in the assimilation of due aliment, 
as to be now fully and profitably susceptible of the action of 
the combined stimuli of the soil and atmosphere. Hence I 
contend, notwithstanding the objection of M. DeCandolle, that 
the maturity of the seed is rightly and legitimately placed in 
the list of the conditions of germination. I do not speak of 
the experiments of the chemist in bis laboratory; I do not 
deny that a seed apparently unripe may germinate; but I 
speak of the operations of the farmer and of the gardener, and 
ask whether or not it would not be thought most absurd in them 
if they were to gather and sow their seeds in an unripe state? 
II. The second condition necessary to germination, or at 
least to rapid and healthy germination, is the exclusion of 
light. The practice of the raking in of the grains, or seeds, 
sown by the farmer or gardener is founded upon this principle. 
But it does not seem to have engaged the notice of men of 
science, or to have heen proved by direct and intentional ex- 
periment till lately. The first direct experiments that were 
instituted on this subject are those of Ingenhousz. He found 
that seeds germinate faster in the shade than in the sun, and 
hence concluded that light is prejudicial to germination. Se- 
nebier, who repeated the experiments of Ingenhousz, had the 
same result, and drew from them the same conclusion*. 
The prejudicial effect of light has been thought to be owing 
to its action on the carbonic acid gas contained in the seed, 
by which its oxygen is withdrawn too rapidly, its carbon 
fixed, its mass parched, and the possibility of its germination 
thus precluded. _ 
But M. DeCandolle denies that the exclusion of light is 
necessary:  L’exclusion de Ja lumiére est trés-loin d’étre, 
* Mem. Phys. Chem. vol. ili. p. 341. 
