14 
THE CHEMIST AND DRUGGIST. 
June, 1882. 
The general term for this membrane is cellulose. Its 
chemical composition is CJ 6 , H 10 , O s . It is the most 
abundant of the solid parts of plants, and the origin of many 
substances transformed out of it. In its purest state it is 
known to us as cotton, this being the “ hairs surrounding the I 
seeds of the cotton plant ( Gossypivm lierbaceum) . Husks of 
seeds, flax, and fibres generally are varieties of cellulose. 
If by pressure cells lengthen in one direction, they fre- 
quently have pointed ends ; if much lengthened tubes are 
formed, such form the greater portion of the wood of the 
plant. When the length and diameter are much increased, 
vessels result ; when by pressure or other cause a mass results, 
formed by many cells adhering, we get cellular tissue, or 
parenehyura. If the vessels are very long, with pointed ends, 
the tissue is prosenchyura ; and when the walls are much 
thickened, elongated, and flexible, the result is pleurenchyura 
(pleura, the side), on account of the support such ribs give to 
various parts. Pleurenchyura forms the woody fibre of plants, 
the material of which ropes, cordage, and mats are formed, 
and from which the more delicate parts have been removed by 
maceration in water — as in the cases of hemp, flax, bass. If 
maceration in water be carried much further pulp results, and 
hence cellulose is readily converted into paper. Pleurenchyura 
is characteristic of vascular plants ; in those entirely cellular — 
as fungi, algas, &c. — decay under the action of water speedily 
sets in and disrupts them, hence probably the reason that 
their fossil remains are so rare, whilst plant remains of vascular 
vegetation are often met with. As cellular tissue is thus 
composed of an aggregate of cells of various shapes, it is evi- 
dent they cannot touch on all sides, hence unfilled parts must 
exist ; such are called intercellular spaces ; they contain air. 
Coming now to the interesting question as to what cell- 
contents are at the outset, the growth of a plant will assume 
a clearer aspect. Firstly there is a transparent liquid or sap. 
Within this is a roundish body called the nucleus or cytoblast 
( llastos , a germ), and enclosing the nucleolus. There is also 
a thick viscid granular slimy body called protoplasm, an 
essential of living cells, always in motion absent from dead 
cells. Protoplasm contains water and organic matters, and 
especially organic matters containing nitrogen. It is the 
most important of cell-contents, as out of it new ones are 
formed. 
Here is also contained the substance called chlorophyll, or 
leaf-green, either as a layer or in granules. This is the source 
of all the green colour in plants. It is only developed under 
the influence of light, or more strictly under the influence of 
the red and yellow rays— the rays exciting heat and luminosity 
— whilst when plants are subjected to the influence of the 
actinic rays only, by being grown under blue or violet glass 
screens, they become quite blanched. For the development of 
chlorophyll, iron is found by experiment to be essential ; 
deprived of iron it ceases to form. If, then, ferruginous , 
matters are administered, it is quickly produced, and the 
plant becomes green. Hence it would appear that plants, like 
animals, are subject to anomia, the same remedy also'effecting 
a cure. From chlorophyll, under various circumstances, the 
colours of .plants are produced. The variegation in leaves is 
due to alteration or absence of this principle ; so are the 
gorgeous tints of autumn, as seen in the “fall of the leaf.” 
Advantage is taken by gardeners of the fact that light is 
essential to formation of chlorophyll in the cases of asparagus 
and celery, for by earthing-up these plants and thus excluding 
light, the secluded parts become quite blanched. Many 
efforts have been made by chemists to utilise chlorophyll as a 
colouring agent in confectionery, the charming tones of green 
not being readily imitated safely ; but chlorophyll, although 
apparently pure green, is composed of two distinct principles — 
phyllo-cyanic and phyllo-xanthic — into which the green 
quickly resolves itself, nor should we be surprised at it 
speedily undergoing organic changes since it is from it that 
Nature forms her varied colours. The two series of colours 
just mentioned were ingeniously tabulated by De Candolle 
into the cyanic, or blue, and the xanthic, or yellow green, com- 
posed of blue and yellow, occupying the middle, whence the 
two series diverge thus : — 
Red 
Orange-red 
Orange 
Yellow-orange 
yellow 
Yellow-green 
Green 
Blue-green 
Blue 
Blue-violet 
► Xanthic series Violet 
I Violet-red 
I Red 
J 
V Cyanic series 
Beyond indicating the above, I need not deviate further 
except to mention that chlorophyll is strongly fluorescent— 
that is, it displays, when properly illuminated and viewed at 
an angle, a spectral colour not ordinarily visible. Sir John 
Herschel referred the phenomenon to epipolic dispersion, or 
dispersion of the rays of light from the first surface of the 
fluid, irrespective of the gross bulk. Fluorescence derives its 
name from having been first studied in Fluor spar, but it is a 
property enjoyed by a great many organic and inorganic 
bodies. In the present case we have a red fluorescence, in 
quinine a fine blue, as also in kerosene oil ; in tannine there 
is a green. And just as there are sounds too deep to be 
audible, too shrill to be perceived by us, so there are colours 
ordinarily invisible until the vibrations producing them are so 
controlled by these fluorescent bodies as to bring them in 
a condition to stimulate the optic nerve. Advantage may be 
taken of this property in analysis to detect admixtures. Thus, 
tannine fluoresces, whilst pure mustard does not. Should the 
sample be fluorescent, it must be sophisticated with a foreign 
body, probably tannine. When cells become matured, in 
addition to cell-sap, protoplasm, and chlorophyll, they contain 
a great variety of other substances. The pulp of an orange 
contains citric acid. In the potato the cells are filled with 
starch, a body readily recognised by the blue colour formed on 
adding iodine to it, as may be observed here. Starch varies 
physically, according to its source ; and by the microscope the 
starch from maize, wheat, potato, arrowroot, sago, tapioca, 
&c., may each be distinguished, but chemically it has the same 
composition as cellulose C 6 , H 10 , O s , and from starch many 
proximate principles are formed, such as sugar, dextrin gum ; 
hence it may be regarded as a reserve food for the formation 
of these and other active matters. Then we have wax, oils, 
fats, resins, balsams, as the contents of cells. In the grass 
family silcia is found ; in rhubarb, onion, squill, banana, 
crystals of oxalate of calcium are met with ; but far the most 
important of cell-contents, physiologically considered, is albu- 
men, corresponding to white-of-egg, a body rich in nitrogen, 
and serving for the support of the young plant, as in the egg 
it does for the young chick during incubation. It is to 
albumen in vegetables that a ropy appearance is due when an 
infusion of herbs is heated, and coagulating at a temperature 
of 160 degs. F., it rises as a scum, or sinks as dregs, enclosing 
within its meshes all suspended matters ; thus liquids are 
clarified. Albumen also contains sulphur, the cause of mus- 
tard spoons and egg spoons, when of silver, becoming dis- 
coloured. 
Frequently in medicinal infusions it is desirable to exclude 
starch and albumen, as that is not dissolved in cold water. 
Whilst this coagulates by heat, a cold infusion subsequently 
heated will remain clearer and brighter than if otherwise 
made. 
The growth of a plant is the aggregate result of the enlarge- 
ment and multiplication of cells. In a fungus the growth is 
especially rapid, but in any case the continuous growth de- 
pends upon the constant growth of new cells. Each cell is 
thought to grow by intersusception or the intercolation of 
fresh particles between those already formed, and not as is 
the case with shells by the deposition of layers on the 
inside. Ordinarily cells are microscopic objects. In the 
cotton, however, they may be one or two inches in length ; in 
the lemon they are about half-an-inch long, still longer in the 
shaddock. Their multiplication takes place in several ways, 
either the entire protoplasm is consumed in forming a new 
one out of those already formed as in a swarm-spore, or two 
cells in close proximity transfer protoplasium matter from one 
to another through a tube, or again by a kind of budding as 
in the grass plant, small, independent cells being thrown off. 
Under varying conditions modifications in the form and 
structure of cells must take place to produce the great variety 
we see in nature. Then there are fibres and vessels through 
which nourishment is conveyed, these often having spiral 
vessels inside, or tubes fashioned into rings. In some vessels 
is found the true juice of the plant or latex, a fluid becoming 
white on exposure to the air. Assafoetida is such a juice 
exuding from an umbeliferous plant growing in Persia, 
Afghanistan, and the Punjaub ; the milky exudation from a 
freshly cut dandelion stalk is another example of latex. 
The epidermis is composed of a layer of tubular cells, the 
cuticle of another layer above this. Stomata or breathing 
pores are cells thickly studding the under surface of the leaf. 
These are also present on the stem, the epidermis, and the 
flower, but absent from the root. Hence by this means the 
true root may be distinguished from the under-ground stem. 
