: 69» . [ 300 ] 
vegetables. Piven are found i in all the pr eat stations. The 
divided into, first, ree which grow on the surface of others, as the Cus- 
cuta and the Misle and, secondly, intestinal parasites, which are de- 
veloped in the valerie of living plants, and tr the  acaaie to ‘lake 
their appearance outwardly, such as the Uredo and 
16. Epiphytes, or false parasites, whieh grow rier cited dead or 
living vegetables, without deriving any nourishment from them. i 
class, which has often been confounded with the preceding, has two dis- 
tinctly characterised divisions. The first, which approaches true parasites, 
comprehends cryptogamous plants, the germs of which, probably carried to 
their stations by the very act of vegetation, develop t themselves at the 
riod when the plant, or that se 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 Spheerias: these are 
spurious itestinal par asites. ‘The second cs a those vegetables, 
whether cryptogamic, such as lichens and Musci, or phanerogamons, as 
mi a which live upon living plants, withoiit deriving any nutri- 
ment from them, but absorbing moisttire from the surrounding atmosphere ; 
these are pipet fial false par rasites. Many of them will grow upon rocks, 
dead trees, or eart 
= s we see that De morn tae ae found it necessary to divide vegeta- 
tion into sixteen stations. I do not attach much importance to several of 
mata because they are vague nd Iidcobite of application, aud frequently 
common to man ants; but it is, nevertneless, useful to bear in mind, 
em o 
any very decided peculiarity of character. This is, indeed, nidiapeesble, 
in order to enable us hereafter to form arly definite appreciation of the n 
ture of the influence of the combined agency of soil, temperature, and ie 
re. 
, and by far the ee important head under which the geogra- 
' phical: disiibation of plants is to be considered, is with reference to tem- 
perature and light. These “depend, fitstly, upon latitude; and, secondly, 
upon ices above these 
As we proceed from the poe towards the equator, we find the tempera- 
ture gradually increasing ; and as we ascend from the surface of the ocean 
ip into the atmosphere, we find the temperature gradually dees tite," un- 
til we reach a point at which perpetual Sew t hol lds his throne, and » where 
oe aria ceases. 
and Prenanthes es spinosa : to these succeed vines, he ane campanula, 
and Mes serschmidin hans sal a ib rd class, consi foes ra gor 
% ' - ? 
ing Viola, and Festuca. Ses umboldt’s Tra 
Therefore, in considering the matter of the Rie RS fot a given climate, 
e+ 
i : Hy 
