DEVELOPMENT. 47 
Germination.—The conditions under which germina- 
tion takes place need not be alluded to at any length, as 
they are the same as those requisite for growth, and 
practically every cultivator knows that air (oxygen), 
moisture, and heat, varying in amount according to the 
plant and according to circumstances, are required, and 
that his success depends in great measure upon the 
proper tillage of the soil which secures these requisites. 
When the seed, or rather the embryo plant within it, 
begins to grow, water is absorbed, the seed swells, the 
insoluble starch stored up becomes converted into glu- 
cose, or a form of sugar, by the agency of a nitrogenous 
substance which acts as a ferment. These chemical pro- 
cesses are accompanied by an evolution of heat and an 
outpouring of carbonicacid gas. Thus is it that in malt- 
ing barley the grain swells, gets hot, and its starch is 
converted into sugar. As the seedling grows, both starch 
and sugar gradually disappear, although the stock of | 
starch is continually replenished so long as the leaves 
continue to act. The nitrogenous constituents of the 
seed undergo similar changes from the insoluble to the 
soluble condition, the latter being capable of transport 
from place to place as may be required. 
The accumulation of insoluble matter in the seeds is 
accounted for by M. Dehérain in this wise. Atthe period 
of maturation the juices of the plant contain the various 
substances held in solution. These juices are directed 
towards the seed or towards the store organs, wherein, by 
virtue of some changes not fully understood, the matters 
previously held in solution become as it were precipitated 
and rendered for the time insoluble. As a consequence, 
the water is deprived of these materials, and to restore 
the balance fresh supplies are drafted from the leaves 
towards the store-organs, there in like manner to deposit 
their starch, their inulin, or albuminoid matter. In the 
case of biennials like turnips, or mangels, during the 
