The embryo consists of an axis bearing two or more cotyledons and ending below in a radicle; it lies in a generally copious food-storing tissue (endosperm) which is the remains of the female prothallus.
On germination of the seed the radicle first grows out, increasing in size as a whole, and soon adding to its tissues by cell division at its apical growing-point.
In germination of the seed the root of the embryo (radicle) grows out to get a holdfast for the plant; this is generally followed by the growth of the short stem immediately above the root, the so-called "hypocotyl," which carries up the cotyledons above the ground, where they spread to the light and become the first green leaves of the plant.
Now this ratio is the same as that which gives the relative chemical equivalents of hydrogen and copper, for r gramme of hydrogen and 31.8 grammes of copper unite chemically with the same weight of any acid radicle such as chlorine or the sulphuric group, SO 4.
- Seeds of Cruciferae cut across to show the radicle and cotyledons.
The free fatty acid radicle then unites with an alkali, and becomes transformed into a soluble soap which is then readily absorbed in this fluid condition by the epithelial cells of the mucous membrane.
Certain others are referred to in relation with the important radicle contained in the salt.
In 1832 he published, jointly with Willer, one of the most famous papers in the history of chemistry, that on the oil of bitter almonds (benzaldehyde), wherein it was shown that the radicle benzoyl might be regarded as forming an unchanging constituent of a long series of compounds obtained from oil of bitter almonds, throughout which it behaved like an element.
These on the one hand resulted in the enunciation of his ethyl theory, by the light of which he looked upon those substances as compounds of the radicle ethyl (C 2 H 5), in opposition to the view of J.
Cotyledons opened to show the radicle a, and the plumule.
One of the earliest, if not the earliest, was the investigation, published in 1830, which proved the polymerism of cyanic and cyanuric acid, but the most famous were those on the oil of bitter almonds (benzaldehyde) and the radicle benzoyl (1832), and on uric acid (1837), which are of fundamental importance in the history of organic chemistry.
In a note published in 18 r.1 he described the physical properties of this acid, but he said nothing about its chemical composition till 1815, when he described cyanogen as a compound radicle, prussic acid as a compound of that radicle with hydrogen alone, and the prussiates (cyanides) as compounds of the radicle with, metals.
1, back, and 2, front view; 3, vertical section, showing (b) the endosperm, and (a) embryo; 4, beginning of germination, showing (b) the pileole and (c) the radicle and secondary rootlets surrounded by their coleorrhizae.
I I, Bennettites seed in longitudinal section, showing the dicotyledonous embryo; p, cotyledons; r, radicle; s, testa.
By further growth this tissue gives rise to a proembryo, which consists, at the micropylar end, of a sac; the tissue at the chalazal end grows into a long and tangled suspensor, terminating in a mass of cells, which is eventually differentiated into a radicle, plumule and two cotyledons.
The growth of the primary root is limited; sooner or later adventitious roots develop from the axis above the radicle which they ultimately exceed in growth.
The soil, it appears, is suited to the seed, for it has sent its radicle downward, and it may now send its shoot upward also with confidence.