The Vegetable Individual in its relation to Species. 181 
tains, not covered by glaciers, grooved and polished surfaces with 
the furrows extending in long parallel lines seeming to indicate 
the action of a former glacier, we should remember the effects 
which may be produced during a long period of time by light 
and loose materials transported in a current of air; and which 
consequently may be produced with greater distinctness, and in 
a different style, by rocks moved forward in a current of water. 
The effects produced by glaciers, by drift, or moving sand, are 
doubtless different and peculiar—so different and characteristic, 
that the cause may be at once assigned by the experienced ob- 
server, who can distinguish between them without difficulty. It 
is, however, possible that after a sand-worn surface, such as has 
been described, has been for ages covered with moist earth, a de- 
composition of the surface would take place sufficient to remove 
the polish from the furrows and leave us in doubt as to, their 
origin. 
If it were possible, it would be exeedingly interesting to ascer- 
tain the length of time it has required for the little grains of sand 
to carve the surface of the granite ridge to its present form. 
How inappreciably small must be the effect produced by a single 
grain! And yet by their combined and long continued action 
mighty effects are produced. That.the action of the grains sin- 
gly, is not visible, is proved to us by the polished surface, for no 
One grain cuts deeply enough to leave a scratch. Ages have 
doubtless elapsed since this action of the sand began, and we 
cannot tell how deep the abrasion has extended; cubic yards 
of granite may have been cut into dust and driven hefore the 
wind over the expanse of the Desert. 
Arr. XVIIl.—The Vegetable Individual in its relation to Spe- 
. Ces ;* by Dr. ALexanpeR Braun.—Translated from the Ger- 
an by Cuartes Francis Srone. 
» Parr ILt 
As I attempted to show in Part I, whatever seems arbitrary 
and indefinite in the existing views of what constitutes the Veg- 
etable Individual has its ground in the nature of plants them- 
selves, which, in their realization are resolved into a plurality 
which they are not eapable of reducing to as complete an unity 
as animals are. As we ascend in the natural kingdoms, individ- 
* Das Individuum der Pflanze in seinem Verhiltniss zur Species—Generations- 
plge, Genrationswechsel und Generationstheilung der Pflanze, by Dr. A. Braun, Pro- 
ssor of Botany in the University of Berlin, dc, dc. 
yi 
