names coming all together. Think of what the names
mean, that you may understand generally what the
tissues are. Take another general look at them in
Fig. 152, and I will tell you a little more particularly
about them when I tell you about wood and bark in
another chapter.
* From the Latin "fundamcntum," from " futtdo," I found, serving
for the foundation.
WOOD AND BARK.
175
CHAPTER XXX.
woo i )
AND BARK.
I AM now going
to tell you a little
more about the
fibro - vascular
bundles ; so let
us look at them
in a buttercup
plant, or in a leafy
branch of bush or
tree, such as the
sycamore or
flowering currant
The fibro-vascular
bundles which
have grown up
within the main
stem of the herb
or tree, have
branched out with and within its branches, and you
can see them as they branch for the last time and
appear as veins in the blades of the leaves.
Fig. 153. Cuckoo pint {Arum tnacnlatitm),
showing spadix, spathe, and sagittate leaves.
FLOWER-LAND.
Fig. 154. Monocotyledonom
stem.
Now I want you to try and understand the two
most common ways in which
these fibro-vascular bundles
are arranged within the stems.
In monocotyledons * they pass
up the stem, scattered about
here and there in the funda-
mental tissue (Fig. 154). But
in dicotyledons * the bundles
are arranged in it so as to form a ring. The
pictures will help you to understand this better, as
they show you the surfaces of two stems which have
been cut across. It
is the ringed arrange-
ment which occurs in
most of our native
trees (Fig. 155). In
Fig. 152 you have
already noticed the
ring of fibro-vascular
bundles (f) surround-
ing and surrounded
by the fundamental
tissue.
But notice the
picture, Fig. 1 52, a little more closely. The bundles you
see are made up of a darker and a lighter part.
Fig. 155. Section of oak, several
years' growth.
The
* From the Greek " ntonos" one; or dis (duo), twice, double, and
cotyledons (cf. pp. 33 and 154). Monocotyledons, plants of which the
seeds have one seed-leaf ; dicotyledons, plants of which they have two.
WOOD AND BARK.
177
innermost and darker part (x) is made up of tissues
which become hard in shrubs and trees, and form the
xylem* or wood. The outer and lighter parts (cb) are
made up of tissues which are called phloem^ or bast.
The wood and the bast do not continue to grow,
but between them is a set of living and growing cells,
called the cambium. These cambium cells form new
* From the Greek " xulon" wood.
t From the Greek " phloios" the inner bark, bast.
13
FLOWER-LAND.
tissues year by year, which in their turn cease to
grow, and form a permanent addition to the already
existing wood and bast bundles, as the case may be.
Fig. 156 C shows you the cambium .bundles very well.
Now get a small branch of ash or elm, oak, syca-
more, or elder, and cut it evenly across. You can
easily distinguish the " pith " and the " wood," and
the softer part which surrounds the wood, which, I
dare say, you call the " bark." Peel off the bark a
little. How easily it comes away, and how slippery
the wood is where it has been taken off. It is
because you have pulled away the bast from the
wood, and the cambium cells which lie between them
are the growing cells, full of protoplasm, increasing
by division, and very tender.
So now you can
understand some-
thing about the
growth of wood. I
do not know how
old that little branch
may be you have
been looking at, so
look at Fig. 157. It
shows you part of
the surface of a four-
year-old branch, cut
Fig. 157. Part of a transverse section of a *
twig of the Lime, four years old. m, the evenly across. Jiach
pith ; x, the wood ; I, 2, 3, 4, four f , cam Kj um
annual rings; c t cambium; ph t bast; > C<
A, bast fibres ; pr, k, outer bark. h as formed new
WOOD AND BARK.
179
tissue, more abundantly on its inner side for wood
than on its outer side for bast, and the former has
hardened year by year into the four rings of wood.
This is how it is that in the trunks of many trees you
can often plainly see the rings of wood as many
rings as there are years in the age of the tree * (cf.
Figs. 157, 155).
In Fig. 1 5 8 you can see
that there are slits or
openings between the
fibro-vascular bundles,
which go from the cam-
bium towards the pith
or medulla. These are
called medullary rays,
and are filled with fun-
i . / Fig. 158. Portion of a stem when cut
damental tissue (paren- across, showing surface (transverse
rhvma"! Tripv nfr-p-n section ) mi '> and surface whe.n cut
1 lengthwise (longitudinal section) a to
add greatly to the h lhe P ith ? m shows medullary rays.
beauty of the wood, as for instance in what is known
as silver grain. In a transverse section of a stem,
these medullary rays appear as rays from the pith
towards the bark (Fig. 157). And compare Figs. 152
* Because the new wood is added to the outside of that already
formed, stems of this kind of growth (dicotyledons, p. 176) have been
called "exogenous" The word is derived from two Greek words
"^-," "exo" outwards, on the outside, and " genu" old form of
" gignomai" to come into being. The stem increases in thickness by-
addition upon the outside of the wood only. When the fibre-vascular
bundles grow here and there amongst the fundamental tissut
irregularly, the plants have been called '''endogenous'" (" endonj
within, and "geno"}. If you cut across a cane, you can see a good
example of this growth ; and see Fig. 154.
i8o
FLOWER-LAND.
and 159, where the fibre-vascular bundles are some
distance apart, showing the fundamental tissue be-
tween them, which in an older and more woody stem
forms the medullary rays of Fig. 157.
There is much more that is very interesting about
the wood, but I must hasten on to tell you a little
more about the bark or cortex*
So let us go back to Fig. 157, and take up again
the little branch you were looking at just now. In
the portion you peeled off
from the wood you have those
parts of the fibro-vascular
bundles which are outside the
cambium. Can you tell me
what they are called ? Yes !
they are called "the bast," and
they form the inner -or secondary
Fig. 159. Cross section of bark or cortex (Fig. 157, ph, b).
Though never hardening
into wood, they cease to grow,
take a permanent form, and
are more or less tough. It is
often very useful. I dare say
you know it very well as the bast, often from the
lime tree, which gardeners use for tying up their
plants. So, again, the bast of the hemp and flax
plants is so much used for making string and linen,
stem of dicotyledon at end
of first year. a, pith ;
c, woody tissue, with
vessels ; d, cambium cells ;
c, bast cells ; fg, outer
bark.
* From the Latin " cortex," the rind or bark.
WOOD AND BARK.
181
that the name of the whole plant often means only
the useful bast which the plant contains.
The outer bark, or bark proper (primary cortex),
consists mainly of fundamental tissue (Figs. 157 pr,
Z 59 /) Generally, upon its outside layer, and
so just under the epidermis, are formed cells, with
walls of cork. This cork cell tissue, through
which water hardly penetrates, prevents nourish-
ment from reaching the epidermis of the young
Fig. 1 60. Transverse section of a one year's shoot
of Ailanthus (foreign), magnified 350 times.
r, primary cortex ; k, cork cells ; c, dead epidermis.
stem, and so towards autumn the once green
and living skin becomes brown, and at length it
withers and dies away. Its place is taken by the cork
tissue, which has caused its death (Figs. 160, 157 k}.
Often the cork tissue grows to a considerable thick-
1 82 FLOWER-LAND.
ness, as in certain kinds of foreign oak, and is
very useful when made into bungs and corks, and for
many other purposes. But you can tell me now
why the outside of the bark is so dry and dead. Yes, it
is because the cork cells hinder the passage of the sap,
and both the cork and any other tissues that may be
outside it become the dry, hard, outside of the bark,
or cortex.
Now turn to Fig. 1 56, and trace . again the wood,
cambium, bast (making up inner bark), and outer
bark ; and notice how the latter is continued into the
dead outside in Fig. 1 60.
In roots the fibro-vascular bundles are differently
arranged ; but this, and other differences of structure
between roots and stems, you will search out in
time to come.
CONl^ENTS OF CELLS AND VESSELS.
CHAPTER XXXI.
CONTENTS OF CELLS AND VESSELS.
Fig. 1 6 1. Monk's Hood (Aconittim napellus}.
c, the root ; e, apocarpous fruit (follicles}.
BEFORE I tell you a
little about various sub-
stances which are some-
times found in the cells
and vessels, I wantyou to
notice certain " spaces "
or " cavities " which are
found in plants. Some-
times they are found
bet we e n
-i
the cells
you re-
member,
and are
then cal-
led"inter-
cellular
spaces"
(Fig. 143)-
1 84
FLOWER-LAND.
But you can easily see some larger cavities, or
air chambers. Cut across some part of a large
water plant, such as the leaf stalk of a water
lily, for instance, and look at it through your
magnifying glass ; or cut through the hollow stems of
the " kecksie," or a grass or rush, some of which you
can find quite easily. You will inquire hereafter how
these cavities are formed.
Now I am going to
tell you about some of
the substances which are
found sometimes in the
intercellular, spaces, as
well as in vessels or cells.
First, then, about the
little green bodies or
corpuscles, which are
embedded in the pro-
toplasm of certain cells.
The green matter which
colours them is called
chlorophyll, so they are
known by the name of
chlorophyll corpuscles. *
It is the presence of
Fig. 162. Transverse section of leaf
stalk of a Begonia, e, epidermis ;
c, cuticle ; cl, a kind of funda-
mental tissue, with cell walls
thickened ; chl, chlorophyll cor-
puscles in the cells ; /, paren-
chyma cell (magnified 550 times).
* Chlorophyll : from the Greek " chloros" green, and " phullon"
a leaf; because it makes the leaves green. Corpuscle : from the Latin
" corpusculum" a little body. These chlorophyll corpuscles are
portions of separated protoplasm, and are very important to the plant.
I will tell you more about them presently.
CONTENTS OF CELLS AND VESSELS.
I8 5
these little bodies that causes the green colour of
so many parts of plants (Fig. 162). But about this,
and the presence of other colouring matter in the
cells of plants, you must try to learn more particularly
after you have read the chapters upon Physiology.
Meanwhile, the more you notice the exquisite colours
which abound in plants, the rich contrasts of flowers
and fruits, so pleasing in their setting of the prevailing
and restful green, the more, I think, you will admire
them. So, also, our common trees will give you many
a beautiful picture in the spring and early summer in
the colours of their fresh expanded leaves, and in the
autumn if you notice them as their leaves begin to
fade and die.
Perhaps you have never
seen the " starch grains "
which are so often found
in plant cells, especially
those of the potato tubers,
beans, or wheat or rice,
and kindred seeds (Fig.
163). If you take a bit
Fig. 163. -Chlorophyll corpuscles of P otato tuber > and Wel1
with starch grains, from a leaf SQak j t so ften, separate,
magnified 550 times, a, 0, c, a, e,
corpuscles of increasing age : in and wash it in water, you
the latter ones the starch fills ...
almost the whole space ; /, g, will presently have a little
^S^l?rt^^S white P wder remaining.
corpuscle has been destroyed, and Look at it through your
only the starchy contents remain ;
b' />" show corpuscle dividing. magnifying glass. Under
the microscope you could
1 86
FLOWER-LAND.
see the starch granules very plainly. Sometimes the
shape of them is very strange (Fig. 164). These
starch granules make the tubers, or seeds which con-
tain them, very nutritious as food. Sugar is found
in the cell sap of the sugar cane, the beetroot, and
some other plants.
Fig. 164. Starch Grains.
Hard "crystals" are also found in the cells of plants.
Here is a picture of some of
them (Fig. 166), but you may
easily find some real ones. Take
a hyacinth stem, break or cut it,
and rub the cut part gently along
a glass slide ; now if you look
through your magnifying glass you
Fig. i6 5 .-Crystals in will very likely be able to see some
the wall of some cell o f t h e crystals like tiny needles
tissue, magnified six
hundred times. (Fig. 1 66). Crystals of this shape
CONTENTS OF CELLS AND VESSELS.
I8 7
are called " raphides."* You would find crystals of
another shape in
stalks of rhubarb.
the
Now we will pick a
dandelion, and notice its
milky juice. It is con-
tained in vessels, long
tubes or ducts, which
spread thickly both in
root and flower stalk. Fig . , 66 ._ Crystals and Raphides .
Common sun's purge also
has a quantity of milky juice which is contained in
cells, and is white in colour as in the dandelion. But
do you know the greater celandine ? t It is a plant
with little clusters of yellow flowers, each of
four petals, and its seed vessel is a pod ; it grows in
waste places, thickets, and often about old houses.
Its abundant milky juice is yellow.
In some plants this kind of milky juice is very
valuable. Opium for instance is the milky juice
which is found in the capsules of a certain kind
of poppy, J and the milky juice of a foreign
plant, of the same natural order as our common
* From the Greek " raphis" a needle.
t Not the buttercup celandine (Ficaria verna), but quite a different
plant, the Chelidonium majus.
| Papaver somnifertttn.
Siphonia elastica.
1 88
FLOWER-LAND.
spurge, becomes, when it is dried,
our india rubber.
I daresay you have often noticed
the " gum " upon the plum or cherry
trees, or the "resinous " substance
upon the firs (Fig. 167). These
are formed in the cells, vessels, and
)w *_ inter-cellular spaces of various parts
ing resin ducts. o f t h e plants in which they are
produced ; as also the
oil or scent which you
find so pleasant when you
bruise a myrtle leaf, or
bend and squeeze the
rind of an orange or
lemon * (Fig. 168).
You see how much there _.
Fig. ib8. Oil cavity with drop of
is for you to enquire about volatile oil (0), from below the upper
surface of a leaf of Dictamnus
and examine, not Only (foreign), magnified 320 times.
concerning the way plants are made up, but also as to
the substances which they contain.
But we must pass on to the way in which plants
live and grow. So I shall conclude our talks upon
the anatomy of plants by telling you about the
beautiful bloom which you often see upon our choicest
fruits. What is the "bloom," and what is it for?
* Notice the leaves of the St. John's wort (Hypericum perforatuni),
which have these oil cavities ; they appear like transparent dots or spots.
CONTENTS OF CELLS AND VESSELS. 189
It is a kind of wax which is in the cuticle (p. 172)
of many plants, and which sometimes forms a
covering or bloom of very minute particles upon
the surface of the fruit, to protect it from being
damaged by the rain.
FLOWER-LAND.
PHYSIOLOGY.
CHAPTER XXXII.
ABSORPTION AND TRANSPIRATION.
IN the first
beginning of life
there is a mystery
which cannot be
explained ; so at
present you must
be content to
know that under
certain conditions
of warmth and
moisture the little
cells of a seed
begin to move
and grow, and the
seed is found to
be alive.
I think you
Fig. i6 9 .-Lily of the Valley (ConvaHaria
majalis). </, stamens with open anthers, showing will be able to
pollen; f, trilocular capsule; g, transverse
section. tell me what the
ABSORPTION AND TRANSPIRATION. IQI
little plant or embryo lives upon until it has burst its
seed coat, and settled itself in the world to enjoy
plant life as its parents did before it. Yes, until its
plumule, becomes a stem, and its radicle a root,
so that it can take its own food from soil and
atmosphere, it feeds upon the store food with which
its thoughtful parent has supplied it, from endosperm,
or perisperm, or cotyledon store as the case may be
(p. 154). You can easily notice the testa of the wheat
or bean seed becoming more and more empty and
withered as the little plantlet grows.
You can see the same kind of thing also in the tuber
of the potato or the orchis, as the young buds grow
and live upon the treasured food.
So now we have come to the young plant, fairly
started and continuing to grow according to the
methods and laws of plant life, about which I am
going to tell you.
What then is the food of plants ? In the first place,
it is composed of certain gases, such as oxygen and
nitrogen, and of certain solids, such as sulphur and
iron, which are mixed up with a great deal of water
into liquid food. For plants take up food by their
roots from the earth in which they grow, and the roots
can only take it in a liquid form. Now let us pull
up some common plant and look at the thinner fibres
of its root ; with a magnifying glass you can some-
times see their root hairs (p. 73) growing from the
epidermal cell's ; and notice also how particles of soil
I9 2 FLOWER-LAND.
stick to them they are taking up from the ground
their liquid food. In transplanting plants, therefore,
you should be careful to injure as little as possible
the ends and finer portions of their roots. This
taking up *by the roots of liquid food is called
"absorption"
Now what becomes of this liquid food, or sap as it
is called ? It ascends from cell to cell, and from
vessel to vessel, passing through their thin walls up
through the stem and branches to the leaves. 1 " But
the plant takes in largely through the leaves some
more food, which it absorbs from the atmosphere.
Great changes take place, and the sap with new
matter in it passes down again through cells and
vessels, forming new substances as it goes, and helping
the plant to grow.
When you know more about chemistry, you will
be able to learn particularly what these changes are
which take place in the sap and substance of the
plant. I will only try and give you a general idea of
the means by which they are brought about.
One of them is the getting rid of some of the water
of the sap. This takes place by evaporation from
those parts of plants which are exposed to the air,
and is called " transpiration" \ The water, in the form
of vapour, is breathed out or given off into the
* cf. diffusion in the Appendix.
t From the Latin " trans ," across, and " spiro," I breathe.
ABSORPTION AND TRANSPIRATION.
193
atmosphere through the thin walls of any cells where
it is not prevented by the cuticle (p. 172).
Now, if you take the
epidermis of some
common land plant,
and examine it under
the microscope, you
will find dotted here
and there upon most
parts of it, especially
upon the leaves, the
little openings, which
are called stomates or
stomata. 1 * Here is a
niH-ntv* nf rarf nf HIP Fi ' 1 7. Epidermis of leaf showing
pictured part or tne stomata (highly magn ified). f f. Figs.
surface of a leaf, very 20, 21, p. 25.
much magnified, which shows a few of them (Fig. 170) ;
but they are very numerous, and are found chiefly
on the under sides of leaves.f The stomate is
generally formed of two sausage or kidney-shaped
cells placed together with the hollowed (concave)
sides facing each other, and so having a little opening
between them as in Fig. 170. But the opening between
them varies according as the cells are more or less
swollen with sap ; and the stomate is also much
* From the Greek " stoma" a mouth : plural "stomata"
t Botanists have calculated that there are more than 100,000 stomata
upon an ordinary sized apple leaf, and more than half a million upon
a leaf of the common lilac.
In water plants the stomates are usually wanting in parts under water,
and are upon the upper surfaces of floating leaves. There are no
stomates upon roots.
14
194
FLOWER-LAND.
influenced by the light to which it is exposed, as well as
by the dryness or dampness of the atmosphere.
Through the stomates transpiration can readily take
place, and it is often very considerable. It has been
calculated that a common sunflower, 3^ feet high,
will give off a quart of fluid in a single day.
I dare say you have noticed the leaves drooping
upon transplanted plants, and that in times of heat
and drought some plants begin to droop much sooner
than others. These are caused by the transpira-
tion of fluid through the leaves more quickly than
a fresh supply can be taken up through the roots.
You will perhaps understand the action of the
stomata better if
you look at Fig.
J 7 1. There you
can see what the
substance or
thickness of a
beech leaf is like.
It is cut in two,
and held so that
you look at the
Fig. 171. Transverse section of a beech leaf cu |- ec jcre very
(magnified 350 times) ; co, epidermis of upper
surface; eu, epidermis of under surface; pa, much magnified,
parenchyma ; st>, parenchyma with cavities ;
j, a stoma. You see how the
stomate opens into a space or air cavity, and so the
surrounding cells of the parenchyma are open to the
atmosphere, and transpiration can easily take place.
FURTHER CHANGES IN THE SAP.
195
CHAPTER XXXIII.
FURTHER CHANGES IN THE SAP.
Fig.
172. Inflorescence and leaf of Dock
(JKumex) ; d, magnified petal.
WE will provide
ourselves with a
common pickle
jar, and about an
inch of a small
candle or wax-
taper bound on to
a bit of wire a
little longer than
the jar, and bend
the wire so that
you can easily
hold the candle
inside and close
to the bottom of
So now I will tell you a little about what takes
place when the plant takes in its food from the
atmosphere (p. 192). There is a gas in the atmos-
phere which is called carbonic acid gas, or carbon
1 96 FLO WE R- LAND.
dioxide, and as I want you to remember it, I will
show you what a deadly gas it sometimes is. So we
will light our bit of candle. Now you shall lower it
down into the jar ; and I will hold the cork upon the
jar's mouth to close it. At first the candle burns all
right, but soon it grows dim and then, yes, now you see
it has gone out. Why is that ? The burning candle
has used up the good air of the atmosphere upon
which its flame could burn or live, and the kind of air
of which the jar is now full is a gas in which the
candle cannot burn any more. Let us take the candle
out, and light it, and see if this is really so. Yes, as
soon as you lower the candle into the jar it goes out.
Now you and I every moment we live are using up
the good air of the atmosphere, just like the burning
candle did in the pickle jar, and breathing out
instead of it the other kind of gas which will not
support our life any more than it would the flame of
the candle.
Have you ever read about the Black Hole of
Calcutta ? It was a small room in which one hundred
and forty-six British prisoners were shut up by the
Sepoys during the Indian Conquest. It was so small
that they were terribly crowded, and when the doors
were opened in the morning only twenty-three of all
the one hundred and forty-six were still alive. They
had been breathing in the good air, and breathing
out the bad gas, until the atmosphere became such
that it would hardly support life any longer ; so
almost all of them died, like the candle flame went
FURTHER CHANGES IN THE SAP. 197
out just now within the pickle jar. If they had been
left a little longer the rest would have died also.
What a wonder that with so many people in the
world, the air does not all get spoilt, like it did in the
Black Hole of Calcutta.
But that bad kind of gas which is always being
produced by men and animals, and in some other
ways also, as you have seen by the burning candle, is
just what the plants want. Under the influence of
sun light they take it in, use up and live upon a part of it,
and give back another part of it to the atmosphere
again to make it pure and ready for our use. For
this carbonic acid gas,* so deadly to us, which the
plant takes in from the atmosphere, comes in contact
with those little green bodies which I told you are
found in certain cells, which are called chlorophyll
corpuscles (p. 184). Then, but only under the influence
of light, the gas and the corpuscle both become