INTRODUUTION TO BOTANY. 
25, 
tion between them is, in fact, a mattei' upon 
which the most learned naturalists are not 
only at variance with each otiier, but often 
altogether at, fault. The difficulty lies on the 
confines of the subject ; not in discriminating 
the characters which refer the oak and the 
elephant to their respective stations, but in 
separating the lower orders, as they are called, 
of each kingdom. To make this understood, 
it may be well just to pen tion, that, according 
to what appear to be the most correct notions 
on this matter, plants and animals may be re- 
garded as two great sections of organic life, 
which at the lower extremity, that is, in the 
most simple forms of each, approach each other 
so closely as to coalesce, but at tlie higher 
extremity, that is, the more compound or per- 
fectly developed forms of each, are widely se- 
parate, the divergence gradually increasing 
from the lowest to the highest forms. It is this 
coalescing point which baiSes the attempts at 
definition ; and as a consequence of the un- 
ci'rtainty or obscurity hanging over the sub- 
ject, there are some organized bodies which 
are sometimes and by some observers claimed 
as animals, and at other times and by others 
considered as vegetabl s. This amounts to 
the statement, that it is a matter of extreme 
difficulty to point out the distinguishing dif- 
ferences between animals and plants ; and so 
in truth it is, viewing the question in the ab- 
stract. The author's definition runs thus ; — 
" A plant is a cellular body, possessing vitality, 
living by absorption through its outer surface, 
and secreting starch," the latter being perhaps 
the most tangilde character. Besides this, 
we have an account of the definitions offered 
by various other botanists, as Jungius, Boer- 
haave, Ludwig, Linnseus, Mirbel, Link, De 
Candolle, Richard, Endlicher, Jussieu, D. P. 
Gardner, and the visionary philosophist 
Oken, the latter of whom says, — " The plant 
is an organic body, chained to tlie earth ; it 
is only developed out of water, and in the 
dark in the earth ; is associated with metal 
and carbon ; is a magnetic needle attracted 
out of earth into air towards light," a state- 
ment which, it is well observed, is tinctured 
with all that mysticism which renders the 
writings of this author so repulsive to sober 
minds. 
The remaining matter is divided into three 
books, of which the first is devoted to organo- 
(j>'aphy, or the structure of plants, which is 
treated at length ; the remainder of the first 
volume and a portion of the second being 
thus occupied. This branch of the subject 
comprehends what relates to the various forms 
of tissue, or elementary matter, of which 
plants are constructed, or to the external ap- 
pearances assumed by the various combina- 
tions of these elementary organs. The term 
tissue is applied to the material which forms 
the structure of plants, and of this there are 
many kinds, the bulk of all the soft parts being 
what is called cellular tissue, which forms, in 
some of its various conditions, the soft part of 
the substance of all vegetables. This is per- 
meated by layers and combinations of different 
forms of vascular and woody tissue, the first 
consisting of vessels for the transmission of 
fluids and air, and the latter consisting of 
fibrous matter serving to solidify and strength- 
en the entire structure. The terms applied to 
the elementary organs are, — 1 . Cellular tissue, 
or f)arenchym ; 2. Pitted tissue, or bothren- 
chyvi ; 3. Woody tissue, or pleu7'enchym ; 4. 
Vascular tissue, or trachenchym; 5. Latici- 
ferous tissue, or cinenchym. These elementary 
matters are constructed of what are called or- 
ganic mucus, membrane, and elementary fibre; 
and indeed, there is no doubt that all the forms 
of tissue enumerated above, are in reality mo- 
difications of one common type, namely the 
simple cell. 
It is a mysterious fact that all plants should 
be compounded out of a simple vegetable cell ; 
and yet, really, this is near the truth, divest- 
ing the subject of its technicalities. At the 
least, this is the light which science seems to 
shed upon the subject. The cell forms within 
itself the nucleus of another or other cells, 
which advance to maturity and become inde- 
pendent only to undergo the same process of 
multiplication ; and thus an increase of size is 
effected. This is carried on under the impulse 
of the vital force of the plant. So of the dif- 
ferent kinds of plants ; the simplest are mere 
cells or vesicles, or threads of vesicles, and 
the most complex are also vesicles connected 
together in indefinite numbers, yet arranged 
upon a definite plan, which gives individuality 
to the connected mass. 
The cellular tissue which is thus regarded 
as the type of all the other forms, consists of 
little bladders or vesicles of various figures 
adhering together in masses ; it is transparent 
and for the most part colourless. Some idea 
of its nature may be gained by cutting a very 
thin slice — not thicker than tissue paper — 
across the pith of any plant, and this if viewed 
by a magnifying glass will be seen to have a 
honeycombed appearance, which, in fact, re- 
presents a cross section of the cells. It is ge- 
nerally transparent and colourless, or at most 
only slightly tinged with green. The brilliant 
colours of vegetable matter — the white, blue, 
yellow, and scarlet hues of the corolla, and the 
green of the bark and leaves — are not owing to 
any difference in the colour of the cells them- 
selves, but to colouring matter of different 
kinds which they contain. When growth or 
extension of the plant is. going on, it takes 
place, as already intimated, by the little blad- 
