222 MEANING OF THE TERMS ENDOGENOUS AND EXOGENOUS. 
or striking plants from cuttings, it is by exposing a part of this mem¬ 
brane to the soil which induces the protrusion of new active fibres 
therein. 
The expansion of an exogenous plant is, therefore, a uniform swell¬ 
ing, as it were, of its exterior, from the time it rises from the seed, 
till it has acquired its utmost stature; the first-formed parts—that 
is, the centre of the trunk, and the exterior surface of the bark- 
falling to decay, while the latest formations are extending gradually 
outwards. 
Now let us turn to a type of those plants which are denominated 
endogenous—the tulip, for example. Of this plant, we see it dormant 
in one season, and growing in another. Its vital, or rather its accres¬ 
cent membrane is not seated on the exterior of the bulb, but within 
and at the bottom of it. At the commencement of the growth, we see 
the outside of the bulb composed of certain parts which have only a 
temporary existence for the protection of the fructification within. In¬ 
stead of these external parts becoming enlarged during the spring 
growth, they are destined to decay, and almost wholly disappear at the 
end of the growing season. Watching the progressive development, 
we see the leaves and the stem bearing the flower all rise from the 
interior of the bulbous stem, all of which die and fall off at the end of 
the season, leaving a successor, not upon the exterior of the plant, as 
takes place in the oak, but in the very centre of the system, to come 
forth in the next year. All other plants, having bulbous stems and 
fibrous roots, are constituted and developed in a similar manner. 
Asparagus is an endogenous plant, with what is called a bundled 
root. The incipient stems first appear as conical buds on the crown of 
the roots, and their development appears as nothing else than a simple 
elongation of the parts originally depressed in the bud, and differing in 
no respect from the development of a shoot of an oak or any other tree. 
It may be urged that the whole of the stem of asparagus is produced 
from the interior of the crown, and so far may be called endogenous; 
but this process is not different from that of a shoot of a dicotyledonous 
tree, which may also be said to proceed from the interior of the branch. 
Asparagus, however, is associated in the natural order As'pliodclecs, 
where many of its congeners are truly endogenous; and, moreover, all 
being monocotyledonous, justifies the connexion. 
But there are many other plants which exhibit the endogenous struc¬ 
ture and development much more conspicuously than asparagus, as the 
Musacece, Pandanea , and Palmce. In the plants of these orders all 
the growth, from the evolution of the first leaf or frond to its utmost 
