BOOK V. 
GEOGRAPHY. 
477 
it becomes most requisite. The former are evidently much 
more robust than the latter. 
15. Parasitical plants ; that is to say, such as are either 
destitute of the power of pumping up their nourishment from 
the soil, or of elaborating it completely ; or as cannot exist 
without absorbing the juices of other vegetables. These are 
found in all the preceding stations. They may be divided 
into, first, those which grow on the surface of others, as the 
Cuscuta and the Misletoe : and, secondly, intestinal parasites, 
which are developed in the interior of living plants, and pierce 
the epidermis, to make their appearance outwardly, such as 
the Uredo and ^cidium, 
16. Epiphytes, or false parasites, which grow upon either 
dead or living vegetables, without deriving any nourishment 
from them. This class, which has often been confounded 
with the preceding, has two distinctly characterised divisions. 
The first which approaches true parasites, comprehends cryp- 
togamous plants, the germs of which, probably carried to their 
stations by the very act of vegetation, develope themselves at 
the period when the plant, or that part where they lie, begins 
to die, then feed upon the substance of the plant during its 
mortal throes, and fatten upon it after its decease ; such are 
Nemasporas and many Sphaerias : these are spurious irdestinal 
parasites. The second comprehends those vegetables, whether 
cryptogamic, such as lichens and Musci, or phanerogamous, 
as Epidendrums, which live upon living plants, without de- 
riving any nutriment from them, but absorbing moisture from 
the surrounding atmosphere ; these are superficial false para- 
sites : many of them will grow upon rocks, dead trees, or earth. 
Thus we see that De Candolle has found it necessary 
to divide vegetation into sixteen stations. I do not attach 
much importance to several of them, because they are vague 
and uncertain of application, and frequently common to many 
plants ; but it is, nevertheless, useful to bear in mind, that 
such distinctions do exist, and to point them out whenever 
they take any very decided peculiarity of character. This is, 
indeed, indispensable, in order so enable us hereafter to form 
any definite appreciation of the nature of the influence of the 
combined agency of soil, temperature, and atmosphere. 
