Part 92. The seed may be compared roughly to an egg. Much as in a hen's egg, for example, we have the shell covering a mass of food material provided for the chick or germ which lies within it, so in the seed (Fig. 279A) we find a protective seed-coat (c) enclosing seed-food (f) and a germ or embryo 1 (e). Much of the food provided for the flax embryo is already stored within the little plant itself; what remains to be absorbed has been likened to the white of egg and is called the albumen 2 of the seed. The embryo within the seed is found upon careful examination to be already a miniature plant, for it has a stem (s) bearing at its lower end the beginning of a root (r) which becomes apparent when the seed sprouts; while at the upper end of the stem are borne a pair of fleshy leaves (1) which after sprouting turn green, and between them a tiny bud (b) which is destined to grow into the stem, leaves, flowers, and fruit of the mature plant. Each of these parts of the embryo has been given a special name. The little stem which bears all the other parts is the caulicle.3Each of the first leaves is a cotyledon.4 The bud at the top of the caulicle is known as the plumule,5 while the rudimentary root at the lower end is called the radicle.6

1 Em'bry-o - Gr. embryon, germ.

2 Al-bu'men - L. albus, white.

3 Caul'i-cle - L. cauliculus, diminutive of caulis, stalk - Gr. kaulos, stalk.

4 Cot-y-le'don - Gr. kotyle, a shallow cup, which some cotyledons are supposed to resemble.

5 Plum'ule - L. plumula, a little plume, which the plumule of certain plants, such as the peanut or almond, somewhat resemble.

6 Rad'i-cle - L. radiculus, diminutive of radix, a root. The term radicle is sometimes used so as to include the caulicle, and caulicle is sometimes made to include the radicle as above defined; but the terms are coming to be understood in the sense here adopted.