INTRODUCTION. 
water that it does not overflow the brim. Every other day glass 
and paper should be removed, and any speck of Marchantia or 
slime removed on the point of a pin, before it has had time to 
overgrow the surface and clog the soil. So treated, and especially 
if a little heat can be supplied, most seed should have germinated 
in a month or so; the seedlings may be pricked out about three 
months after that, and in another three will be quite ripe for 
their permanent place in the garden. 
Some, however, are much smaller and more deliberate in 
growth than others; and, above all, some seed, even when quite 
happy and sound, is very much slower to germinate than others. 
The pot, therefore, should not be despaired of in such cases, until 
it has stood barren for more than two years. Conspicuously slow 
of germination are many a Ranunculus, Paeonia, Hellebore, and 
Aconite. Primulas, too, have a capricious way of lying low until 
their second season. On the other hand, a Dianthus, Poppy, 
or Columbine that does not spring up within six months of sowing, 
at the very outside, may well be looked on as beyond hope. The 
biology of seeds is indeed a profound and subtle mystery, involving 
chemical changes and correlations of the utmost delicacy. The use 
of heat is evident, whether engendered by pipes or assisted by 
the pervasive radiance of the sun; the uses of cold are equally 
certain and far more striking, but unfortunately snow is not so 
easy to command as warmth. At the same time, even a few 
hours of driven snow on a seed-pot will have an almost magical 
effect in eliciting seedlings. Up spring the little plants im- 
mediately it has melted, and if only we could secure an artificial 
supply of permanent snow for our pots, there is no doubt that 
all germination would be far more prompt, sure, general, and 
unanimous. As it is, we have to be content with serving every 
opportunity of opening our frames to snow, and heaping it upon 
the pans of seed ; the rest is a matter of experiment, and lies as yet 
behind unlifted veils of science. We only know that alternations 
of cold and heat, drought and damp, act like charms upon the 
seed. If pots can be kept dry for a time, and then damp ; kept piled 
with snow for a period, with alternative sojourns in a dry cellar, 
Ixi 
