542 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[January 11 , 1873. 
to imitate this artificially, so as to produce real qui¬ 
nine by chemical methods. 
I am confirmed in the opinion expressed in my 
* Quinology ’ that the alkaloids must be regarded as 
highly complex and, so to speak, annualized pro¬ 
ducts of the general (or nocturnal) as opposed to the 
chlorophyllian respiration, being in this way fitted to 
act powerfully on the animal economy, the blood 
having an alkaline reaction ; as, conversely, acid 
gases °of simple 'constitution (sulphurous, nitrous, 
etc.) are deadly poison to vegetables whose juice 
has an acid reaction. 
THE MICROSCOPE IN PHARMACY. 
BY HENRY .rOCKLTNGTON. 
('Continued from p. 383.) 
My notes on the structure of the woods of the 
Pharmacopoeia are not sufficiently complete to enable 
me to proceed to describe them at present with com¬ 
fort to myself or justice to my readers. I have, 
therefore, deemed it preferable to take the baiks 
first. The woods that are chiefly remarkable for 
their colouring matters will be taken last of all, and 
will be discussed with especial reference to the 
optical qualities of these colouring matters, some, 
at least, being more complex than I believe is 
generally supposed. The structure of bark differs 
sufficiently from that of wood to require slightly 
different treatment in preparing it for the micro¬ 
scope. The great point is to avoid too prolonged 
maceration, liicli is apt to render the more delicate 
portions so soft as to yield under the pressure neces¬ 
sary to push the razor through the other portions. 
Usually a few minutes, or half an hour, in warm 
water will make the softer barks quite soft enough 
to permit good sections to be cut. The harder and 
more dense barks will of course require longer 
maceration; in practice it will be found to be best to 
make frequent examinations of the portions in soak, 
that the right moment for removing them may be 
seized. Sections should always be mounted either 
in fluid or in glycerine jelly, and a specimen of each 
should be carefully stained with magenta, and a third 
one with a purple solution of logwood and alum, as 
the position, size, and shape of the liber are rendered 
easily visible by the use of these reagents. 
Those who are interested in vegetable structure, 
are wor kin g up for an examination in structural 
botany, or desire to make themselves thoroughly 
familiar with the structure of bark, will find it of 
great value to begin their work upon young shoots, 
and to work by progressive stages from shoots of one, 
two, three, and four years’ growth to the bark of 
full-grown trees. This is a very good period of the 
y.-ar in which to begin this work; and to keep steadily 
at it through the winter, till the spring brought into 
notice a new formation, would be to occupy oneself 
with an interesting as well as an instructive re¬ 
creative pursuit. The use of carmine and magenta 
staining fluids, and in some cases of the logwood* 
and alum solution now much used in some histo¬ 
logical laboratories, will permit of much useful work 
* A convenient way of applying this reagent is to immerse 
the section c.t bark in'infusion of logwood for a few minutes, 
remove , it to a slide and add a drop of ammonia. Wash in 
alcohol in water, and mount. 
being done until but moderate manipulative skill and 
low powers of the microscope, and one or other, of 
them should always be employed. The following 
brief biography of bark will perhaps be of service to 
the student as giving him some notion as to what to 
look for. It is at first composed of precisely similar 
tissues (irregularly shaped, more or less globular 
parenchyma cells) to that of the stem from which it 
lias begun to be differentiated. The next stage 
appears to be the formation of elongated cells 
between the stem and itself, and these are presently 
developed into the “bast layer” liber or Endo- 
phlceum. It is at this stage that the use of staining 
fluids is especially of value, as they bring into notice 
changes that might otherwise escape observation. 
Contemporaneously with the bast, or liber, the outer 
cells become hardened or otherwise changed into 
the Epiplilceum or corky layer, the middle portion or 
Mesopliloeum retaining its active vital powers 
longest, as evidenced by the action of carmine fluid, 
and yet more decisively by the presence of chloro¬ 
phyll and other cell contents. The Epipliloeum may 
strictly be regarded as dead tissue, and is often 
thrown off at intervals. The middle layer alone 
can be regarded as actively long. It only retains 
active vitality so far as regards power of growth for 
a somewhat limited period ; and all increase of the 
diameter of the bark circle takes place within the 
region commonly known as the cambium region, 
between the now woody portion of the stem ancl the 
earlier liber layers of the bark ; and finally various 
modifications of the component tissues of the bark 
and of the bark as a whole take place in consequence 
of successive secondary deposits within the liber 
cells, and of pressure from the expanding stem 
within, and atmospheric influences without. The 
record of most of these may be found in sections pre¬ 
pared for the microscope. 
Mezerei Cortex— The barks of Daphne Mezereum 
and D. Laureola do not differ sufficiently widely to 
render it needful to describe them at great length. 
The latter is easily obtainable in a fresh state, and 
on this account is the one most likely to be selected 
for examination. Neither of them present any great 
difficulties, unles it be desired to obtain transverse 
sections showing the structure of the long fibrous 
and very tough liber common to all the plants of 
this genus. The only differences between the two 
species named consist in the development of the 
parenchymatous cortical substance and in the size of 
its cells and those of the outer cuticle. Sections should 
be cut in two directions, across the stem (transverse), 
and towards the centre of the stem longitudinally 
(vertical). Sections may be also cut longitudinally 
in a direction across the medullary rays of the stem 
(radial), but will not be of much service in this case. 
Logwood stained .sections are the most useful. In 
such a section, if it be a transverse one, we . see, 
beginning at the exterior, first the cells of the epider¬ 
mal layers deeply stained; beneath this are the cells 
of the cork layer unstained; and beneath this are 
well-stained, large-sized parenchymatous cells and a 
largely developed fibrous liber, which does not stain. 
The liber is best seen in vertical sections. Apart 
from the liber there are no special features that need 
detain us. Before passing to a more important bark 
I w r ill mention that the wood structure of the stem 
of D. Laureola (the spurge-laurel, of the hedgerows 
in some parts) is specially interesting, on account of 
the peculiar spiral and dotted markings and pits on 
