favourable for the Growth of Seed. 
47 
placed adjacent to the bulky portion of the seed, consistInj2^ of 
starch mix(>d with gluten and albuminous matter, and the whole 
is enclosed in a coat of dense vegetable matter. 
The growth of the seed consists in the development of the 
germ into a perfect plant, and is known as germination. Sup- 
posing the conditions of growth to be favourable, the first pre- 
liminary is a softening of the coat of the seed, by which means 
water gains an entrance,. and having pervaded the mass causes 
it to swell freely. When the water reaches the germ of the seed 
the gluten or albuminous matter near to it undergoes a chemical 
change, and we have a very important and powerful body formed 
which is known as diastase. Whether or not the germ in 
any way participates in this change, we have no proof; but, if 
not, it is certain that at least by its presence it exerts a controlling 
power. The same addition of moisture to any other portion of 
the seed would not produce the same effect, for this agent (dia- 
stase) is only found in close proximity to the germ, and its exist- 
ence in the seed appears to be simultaneous with the first stage 
of germination. Upon the diastase thus formed devolves the 
important office of preparing food for the growth of the germ ; 
for the bulk of the seed, although abundant in quantity and 
exactly suitable in its constituent elements, is not ready for use 
until it has become soluble in water, and thus been made capable 
of entering into the circulation of the germ. This is accom- 
plished by means of the diastase, by the agency of which the 
necessary supplies are prepared, so long as the store of food in 
the seed is needed. An immediate extension of the cellular 
matter accompanies the entrance of the food into the circulation, 
and we have the external evidence of life by the sprouting of the 
seed. In whatever position the seed may be placed, the radicles 
at once strike perpendicularly down into the soil, and the tender 
rootlets fix themselves there with but little delay. As soon as 
this is effected, the gemmule grows in the opposite direction and 
becomes developed into the stem and leaves of the plant. 
The conditions which control the growth of seeds are, the 
presence of air, moisture, and warmth ; and, to produce healthy- 
germination, all are required in definite proportions. When 
seed is protected from these agencies it will retain its powers 
of growth for long periods of time. Thus, wheat, preserved 
in Egyptian mummies between 3000 and 4000 years, has, after 
that lapse of time, germinated and produced a large increase. 
The preservation of the power of growth is entirely dependent 
upon the seed being kept from those agencies which would excite 
its vital energy : moisture is the first essential for germination, 
as it is in consequence of the chemical action excited in the seed 
by the entrance of water that the seed is aroused to action ; and 
