DEVELOPMENT. Ws 
have this perisperm surrounding their embryo. A simi- 
lar substance is found in the seeds of mangel ; the seeds 
of turnips, peas, beans, and clover, on the other hand, 
are destitute of it. Anembryo plant consists of a radi- 
cle, or rudimentary root, surmounted by a caulicle, 
which is often so short as to be imperceptible to the 
naked eye, but from which spring the seed-leaves, or 
cotyledons—one only in the case of all the cereals and 
grasses, two in the case of the other crops of the farm. 
In the case of the wheat grain, where the perisperm is 
abundant, the cotyledon is small and thin; but in the 
pea or bean, where the perisperm is absent, the cotyle- 
dons are very thick and fleshy. The difference depends 
upon the presence, in the one case, of large quantities of 
reserve-materials in the embryo itself, while in the case 
of the wheat the reserve-materials are stored up in the 
perisperm. 
The seed, then, in addition to the young plant, con- 
tains in the tissues of the embryo plant itself, or in the 
perisperm surrounding it, reserve-materials destined to 
supply the young plant with food during its growth and 
development. 
Reserve-materials: their Transport.— Under the 
head of nutrition, mention has been made of the sub- 
stances formed in plants through various agencies. Some 
of these are used up at once during growth, while others 
are reserved for future use, having usually undergone 
some change in constitution to fit them for their purpose. 
Speaking broadly, these reserves are either starchy, oily, 
or albuminoid (nitrogenous) in their character. The 
starchy or oily ingredients are the direct products of the 
action carried on under the influence of sun light in the 
cells containing chlorophyll. Starch cannot be formed 
in cells containing no chlorophyll, nor, for a continuance, 
in chlorophyll-containing cells, unless they are exposed. 
