TERMINOLOGY. 119 
mule, (plumula). The seed Hedley is covered with 
a double integument, the outer one being thick and 
of a firm consistence, the inner transparent and ten- 
der. The external one is called the external tunic, 
(tunica externa), the inner, the internal membrane, 
(membrana interna). ‘The place in the seed. which is 
occupied by the corculum may be seen externally, 
as it is marked by a deep impression called the eye, 
or external scar, (hilum). ‘The seed, till it has at- 
tained its full ripeness, is fastened by a small thread 
called the umbilical cord, (funiculus umbilicalis). 
Plants have been divided according to the various 
ways in which the seed germinates; viz. such as” 
have no seed-leaves are called acotyledonous, (acoty- 
ledones) ; such as have one, two, or more seed-leaves, 
are called monocotyledonous, &c. (mono, di, polyco- 
tyledones). But an accurate observation of nature 
shews the above division to be inept. In what dif- 
ferent ways seeds germinate will be shewn in the 
Physiology, § 245. 
The forms of the seed are very various, but they 
are easily distinguished. By means of the umbili- 
cal cord, seeds are attached, in the pericarpium, 
either to the rim, to the receptacle, to the inner sur- 
face, to the valves, &c.; but when they are found 
so close in a berry that their attachment cannot 
easily be seen, they are said to be nidulant seeds, 
(semina nidulantia). ‘The substance of seeds is firm, 
and we have but few examples of soft seeds, Lin- 
nzus sometimes speaks of two-celled seeds, (semina 
bilocularia); but such can no more occur in nature 
H 4 than 
