395 
THE PRINCIPLES OF BOTANY. 
By Professor James Buckman, F.L.S., F.G.S._, &c. 
[Continuedfrom ^. 331.) 
As the produetion of the seed is a crowning act in the life 
of a plant, so it will be the last organ that we shall have to 
describe. 
The seed is the reproductive organ of the fruit and is en¬ 
closed in the pericarp, having its own particular integuments, 
the general term for which is the testa ; e.g. the skin of the 
bean or pea, the skin of the chestnut. The body of the bean 
when the testa is removed is called the albumen, and is the 
nutritious part of the seed. At one side of the bean will 
be found a rounded point, the radicle, which in germination 
proceeds downwards, and afterwards becomes the root, while 
a bunch of embryo leaves, the plumule, is the commencement 
of the future plant. 
Seeds are fastened to the placenta by an attaching liga¬ 
ment called funiculus, terms the meaning and significance 
of which will be readily understood by the anatomist, who, 
indeed, will view the seed as an embryo. In the bean wilt 
be seen an oval spot where the umbilicus was attached; this 
is termed the hilum. 
At the end of the hilum of the bean will be seen a minute 
orifice; this is called the micropyle, and its presence in peas 
and beans causes these seeds to readily harden when ex¬ 
posed to the atmosphere. All the parts of seeds, as is the 
case in other plant organs, vary much in form, size, colour, 
and consistence; differences which render some seeds econo¬ 
mically valuable, while others are quite useless. 
A further examination of the albumen of the bean -will 
show it to be readily split into two distinct portions. Coty¬ 
ledons which in turnips, mustards, &c., form the first coty¬ 
ledon leaves; whilst in wheat or barley the albumen is not 
capable of splitting, and its first leaves are in all cases the 
expanded plumule. These facts, which are united to others 
of great significance, as the distinctions in the growth both 
of wood and leaves, form the basis of the classification of 
flowering plants into monocotyledons and dicotyledons. 
Professor Bindley formed another large class of the naked- 
seeded plants which comprehended the Conifera, called 
Gymnogens. In the lower tribes of plants the seeds are 
more simple in structure, being for the most part simple 
