BOTANICAL PRINCIPLES. 59 
tion is effected by the dispersion of grains or spores, which 
are usually generated in the substance of the plant, and 
eem to have but little analogy with true seeds. Hence the 
vegetable kingdom is separated into two distinct groups, 
namely, the flowering (Phanerogamia), and the flowerless 
(Cryptogamia or Agamia). As the former usually possess 
a highly developed system of spiral and other vessels, while 
the latter are either altogether destitute of them, or have 
them only in a few of the highest orders, and those in a 
peculiar state, the flowering plants are termed Vasculares, 
and the flowerless Cellulares. And as all the flowering, or 
vascular plants, when they form stems, increase by an ex- 
tension of their ends, and a distension or enlargement of 
their circumference, but the flowerless or cellular plants 
form their stems simply by the addition of new matter to 
their points, the latter are called A crogens, signifying increase 
from the summit. 
Flowering plants are also for the most part furnished 
with respiratory or breathing organs (stomata), of which the 
flowerless vegetables are to a great extent destitute. 
The flowering or vascular plants are also divisible into 
two well marked groups, namely, the Haogens, or Dicoty- 
ledons, and the E'ndogens, or Monocotyledons. 
The ExocEns (growing from without), increase by the 
addition of new woody matter to the outside of the stems 
beneath the bark ; and they are further characterized by 
the embryo having two or more cotyledons, or seed-lobes, 
hence they are also called Dicotyledons ; such as the Elm, 
Beech, &c. 
The EnpDoGENS, as we have previously stated, increase by 
the addition of ligneous matter to the inside of their stems 
near the centre ; and as the embryo in this class has but one 
cotyledon, they are likewise termed monocotyledons, as the 
Cane, Palm, &c. Again, exogenous plants have the young 
external wood connected with a central pith, by medullary 
