CHAP. II. 
ROOT. 
85 
its deviation from the ordinary characters of Endogenous 
structure is much less considerable than it seems to be at first 
sight. 
According to Mohl, the structure of an Exogenous and an 
Endogenous stem, during the first year of their growth, is al- 
together the same ; but in the second year the wood and the 
liber of the former separate, and new matter is then inter- 
posed ; while, on the contrary, in Endogens no such separa^ 
tion occurs, and consequently the newly-formed matter of the 
stem is forced towards the centre, through which it passes, 
with a constant tendency, however, to reach the outside. This 
statement must, however, be received with distrust ; because 
any one may satisfy himself that the new shoot of an Aspara- 
gus and of an Elder-bush are totally dissimilar. 
Sect. III. Of the Root^ or descending Axis, 
At or about the same time that the ascending axis seeks 
the light and becomes a stem, does the opposite extremity of 
the seed or bud bury itself in the earth and become a root, 
with a tendency downwards so powerful, that no known force 
is sufficient to overcome it. Correctly speaking, nothing 
can be considered a root except what has such an origin ; for 
those roots which are emitted by the stems of plants, are in 
reality the roots of the buds above them, as will be hereafter 
explained. Nevertheless, nothing is more common than even 
for botanists to confound subterranean stems or buds with 
roots, as has been already seen. (See Bulb, Tuber, Soboles, 
&c. &c.) 
Independently of its origin, the root is to be distinguished 
from the stem by many absolute characters. In the first 
place, its ramifications occur irregularly, and not with a sym- 
metrical arrangement: they do not, like branches, proceed 
from certain fixed points (buds), but are produced from all 
and any points of the root. Secondly, a root has no leaf-buds, 
unless indeed, as is sometimes the case, it has the power of 
forming adventitious ones ; but, in such a case, the irregular 
manner in which they are produced is sufficient evidence of 
their nature. Thirdly, roots have no scales, leaves, or other 
G 3 
