1864] 
AMERICAN AGRICULTURIST. 
177 
What is Inside of a Plant. 
The series of articles under this head was in¬ 
terrupted by the crowd of other matter last 
month. Those who have followed them atten¬ 
tively will recollect that it has been shown that 
the plant in all its parts is made up of cells 
varying in shape and size, but in all cases ex¬ 
ceedingly small, and that all of them are clos¬ 
ed, having no visible openings. It is evident 
from what has been said that the growth of the 
plant consists in the increase in number of these 
cells, and this is accomplished by the division 
of cells already existing. There are some plants 
of very simple structure, whose 
growth can be watched, and they 
' give a good idea of the way in which 
cells are multiplied in all plants. 
F l —plant Some kinds of green scum from 
or one cell, fresh water pools are found, when 
seen under the microscope, to be a mass of very 
simple plants, so simple that each one consists of 
only a single cell. Fig. 1, shows one of these plants, 
a single cell filled with green matter. In time the 
green contents of the cell divide, as in fig. 2, a cell 
wall grows over each part, the old cell contain¬ 
ing them breaks away and two plants come 
forth, each of which, after growing to the size 
of the original, repeats the multiplying opera¬ 
tion. At fig. 3, a similar plant is shown divid¬ 
ing into four. In this simple plant we have in 
the first place the division of the cell into two 
or more, and afterward the growth of these 
small cells to the size of 
the original. All plants 
increase in size thus—the 
already formed cells sub¬ 
dividing and those new¬ 
ly formed in this way 
growing to the size pe¬ 
culiar to the kind of p, 
plant. As there are or¬ 
dinarily many millions of cells contained in the 
space of every cubic inch, it is evident that in 
quick growing plants they must multiply with 
wonderful rapidity. Before taking especial no¬ 
tice of the contents of the plant cells it is well 
to consider the manner in which liquids pass 
from one cell to another. We know in a gen¬ 
eral way that the roots take up liquids from 
the soil, and that these are conveyed to the 
leaves where they are evaporated and otherwise 
greatly changed before they are fitted to contrib¬ 
ute to the growth of the 
plant. From what has been 
seen of the internal structure 
of the plant we know that 
there are no long tubes or 
veins, for the movement of 
the sap, as many suppose, 
but its whole circulation con¬ 
sists in a transference of the liquid from cell to 
cell. Though the microscope shows no opening 
communicating between adjoining cells, yet their 
walls will allow the passage of liquids. There 
are several forces at work to cause the rise of 
crude sap into the tissues of the plant, one 
of which is evaporation. That this goes 
on at a large rate is well established by experi¬ 
ment ; a sunflower three feet high has been 
found to evaporate nearly a quart of water dur¬ 
ing the day. The amount which passes off 
from the leaves by evaporation must be supplied 
from the root. Some idea of the part which 
evaporation plays in causing the rise of liquids 
in the plant may be had from a simple experi¬ 
ment, shown in fig. 4, which represents a small 
. 2. CELL DIVIDING. 
funnel with its neck drawn out into a long tube. 
The mouth of the funnel is covered with a 
piece of bladder, both it and its tube being com¬ 
pletely filled with water; it is then placed with 
its lower end dipping in mer¬ 
cury and supported in an up¬ 
right position. Evaporation will 
go on from the surface of the 
bladder and as the water passes 
off in this way the mercury 
will rise to supply its place and 
in time fill the tube. Mercury 
we know to be fourteen times 
heavier than water, and, as we 
have not space to state the rea¬ 
son of this rise, we may say, 
in language which, though not 
scientifically accurate, will ans¬ 
wer our purpose, that the force 
of evaporation has lifted an 
ounce or more of mercury 
through a space of several inch¬ 
es. Another and peculiar force 
is at work within the plant 
which may be briefly stated 
thus: when two liquids of un- 
Fig. 4.— EVAPOit- equal density are separated by a 
ation. membrane through which they 
can pass, they tend to mix, but the light liquid 
passes through the membrane into the dense one 
much more rapidly than the heavy liquid pas¬ 
ses into the light one. This force, called os¬ 
mose, can be illustrated by an experiment with 
the long tubed funnel of figure 4. Over the 
mouth of the funnel a very thin piece of 
bladder is tied, and the funnel part is filled 
with molasses and water, and then set in a ves¬ 
sel of pure water as in fig. 5. We here have 
the lighter water, separated from the heavier 
syrup in the funnel by means of the blad¬ 
der. The flow of the water through the mem¬ 
brane into the funnel will be much more rapid 
than the flow of the sweetened water out of it, 
and the consequence will be that the liquid will 
rise in the tube. This ascent of the liquid will 
take place through several feet of tube and if 
this is bent over as in the figure, the liquid will 
flow out in drops. This action 
will continue until the con¬ 
tents of the funnel and of the 
vessel become of equal density. 
Now let us imagine a single 
series of minute plant-cells ex¬ 
tending from the leaf to the 
ends of the roots of the plant. 
We have here a great number 
of small closed bags containing 
liquid, the upper ones of the 
series being in the leaf where 
evaporation can take place, and 
the lower ones in contact with 
the soil. By evaporation the 
contents of the uppermost cells 
will become thickened and a 
flow will set in from the cells 
just below them: and as the 
density of the contents of these 
cells changes they will draw up¬ 
on those below, and evapora- 
Fig. 5.— osmose, tion alone will be sufficient 
to set a flow in an upward direction. To 
this is added the force of osmose; where the 
contents of adjoining cells are of uneqal densi¬ 
ty, there is as we have already seen a powerful 
tendency of the two to interchange. There are 
other conditions, such as the chemical nature of 
the cell contents which modify the transfer¬ 
ence of the liquids from one cell to another 
which can not well be stated here, but from 
what has been shown of the internal structure 
of the plant and the illustrations of the effect of 
evaporation and osmose here given, it will be 
evident that the juices of the plant are trans¬ 
ferred from one part to another in obedience to 
very simple physical laws. 
How do Flowers Become Double? 
The question is frequently asked of the Agri¬ 
culturist, how this or that flower “ can be made 
to bloom double.” There is no way in which 
double flowers can be pro¬ 
duce at will. There are na¬ 
tural tendencies in many 
plants to become double, and 
these manifest themselves in 
two ways; one is the pro¬ 
duction of two or more pet¬ 
als in the place of one, and 
another is the readiness with 
which stamens are convert¬ 
ed into petals. An illustra¬ 
tion of the fact that the last 
Fig. 1.—stamen, really takes place, may be 
seen in a half-double rose, where stamens may 
be found in the 
transition state, so 
to speak, that is 
part stamen and 
part petal. Fig. 1, 
is a rose stamen, 
fig. 2, a petal, and 
fig. 3, a stamen that 
is half of each. 
Many other double 
flowers will afford 
interesting illustrations of this kind. In the Com¬ 
posite-family to which the Aster, Dahlia, Mari¬ 
gold, Sunflower, etc., belong, what 
usually passes for a flower is in 
reality a collection of numerous 
small flowers gathered closely into 
a head. There are in most plants 
of this kind cultivated for ornament, 
two sets of flowers. Those in the 
center of the head of a single one 
of those noted above, are small and 
tubular, with small teeth at the top 
as in fig. 4. The flowers on the cir¬ 
cumference of the head are much 
Fig. 3. hale larger and instead of being tubular, 
petal. are fl at an d r ibbon-like as in fig. 5. 
This is just as if fig. 4 had grown larger and been 
split down on one side, and then spread out 
flat. The doubling of flowers of this kind con¬ 
sists in the conversion of the flowers like fig.4 
Fig. 5. Fig. 4. 
into those like fig, 5. These changes or sports 
take place in some plants in the wild state, but 
they are more likely to occur in cultivated ones. 
When a tendency of this kind is noticed, the 
