494 The Rev. P. Keith on the Conditions of Germination. 
perfectly dry. Water, therefore, or some liquid equivalent 
to it, is essential to germination. Hence rain is always ac- 
ceptable to the farmer or gardener immediately after he has 
sown his seed; and if no rain falls, recourse must be had if 
possible to artificial waterings. But the quantity of water ap- 
plied is not a matter of indifference. There may be too little 
or there may be too much. If there is.too little, the seed dies 
for lack of moisture; if there is too much, the seed rots. This 
condition M. DeCandolle admits also to be good. 
V. A fifth condition necessary to germination is the access 
of atmospheric air. Seeds will not germinate if placed in a 
vacuum. Ray introduced some lettuce-seeds into the receiver 
of an air-pump, which he then exhausted; but the seeds did 
not germinate. Yet they germinated upon the readmission of 
the air, which is proved by consequence to be necessary to 
their germination. Whether the whole of the ingredients of 
the atmospheric air are necessary, or only part of them, we 
do not at present inquire; but we are willing, with M. De 
Candolle, to limit the part necessary to oxygen. 
Such are the five conditions which I enumerated as indis- 
pensable to the success of the process of germination; and 
I still persist in maintaining the correctness of the enumera- 
tion, notwithstanding all that M.DeCandolle has written 
about the germinating of immature seeds, or the non-necessity 
of the exclusion of light. By demolishing the two first of the 
above conditions M. DeCandolle leaves only three behind. 
But what would M. DeCandolle say if I were to come forward 
with an objection professing to demolish one of the three con- 
ditions which he has suifered to remain? The presence of 
water he regards as an essential condition. But I have ac- 
tually known acorns to germinate, by protruding a radicle 
several inches in length, though lying in the corner of a dry 
granary where no water had access to them at all. Such an 
objection, undoubtedly, would be but frivolous and vexatious, 
—a light in which some might be apt to regard the objec- 
tions which have been taken notice of above. For to say 
that the maturity of the seed and the exclusion of light are 
not necessary conditions of germination seems to be counter 
to the opinions whether of the practical cultivator, or of the 
speculative phytologist. What says Evelyn on the subject of 
the maturity of the seed; and of the exclusion of light ?— 
“Choose your seed of that which is perfectly mature, pon- 
derous, and sound.” (Sylva, chap. i. sect. 2.) ‘* Keep your 
newly sown seeds continually fresh, and in the shade, as much 
as may be, till they peep.” (Sylva, chap. xxxii. sect. 2.) Now 
this is quite in keeping with the physiological doctrines of the 
