June 15, 1872.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
1005 
THE MICROSCOPE IN PHARMACY. 
BY HENRY POCKLIXGTON. 
(Continued fromp. 921.) 
Jalapa. —Tubercule or tuber of Exogonium ( Ipo - 
mcea) purga. Tlie general character of the tuber is 
sufficiently unlike the structure of the ordinary 
‘ root ’ to make its inclusion here somewhat a digres¬ 
sion, for which perhaps my readers will be thankful, 
as a relief from general tedium; the more so, as 
they will be saved from the technical description 
needful with many roots and the like. With the 
general characters of the jalap tuber, its appearance, 
colour, weight, and resinous fracture all pharmacists 
are familiar. These characters are all the concomi¬ 
tants of certain microscopic characters. The dark 
brown, almost black, colour of the exterior is confined 
to the cells of the layer immediately below the true 
epidermis. The cells of the epidermis are oblong 
in shape, much compressed, that is, thin, and have 
their front walls much thickened. The cells which 
contain the dark resinous colouring matter lie imme¬ 
diately below this, and are rounder in outline. Very 
considerable care and patience is needed to render 
these details visible in the dry tuber; in the form of 
powder they cannot be recognized at all; a few 
pieces of brown structure are all then discernible. 
The structure of the interior of the tuber is more 
characteristic, and may be described as being com¬ 
posed of a series of lamelke, each of which consists 
in the middle of irregularly shaped cells with vary¬ 
ing contents, and, on the exteriors, of more regularly 
shaped, more compressed parenchyma cells and vascu¬ 
lar vessels, with exceedingly little pleurenchymatous 
and parenchymatous tissue. Some of the cells 
of this act as resin receptacula, others contain 
starch, and a few are nearly empty of all except the 
usual protoplasmic matter. The starch-bearing 
cells are irregularly hexagonal in shape, cell walls 
are thin and imperforate. The starch granules are 
large, vary much in size and shape, and lie loosely 
in the cells. They may be classed as aggregated 
and isolated granules. The aggregated granules 
usually consist of three triangular granules, the 
bases of the triangles being curved outwards, so that 
' the resulting granule is muller-sliaped, but ap¬ 
proaching the circular. Many of the isolated 
granules are nearly circular, flattened, with a tri- 
radiate, indistinct liilum. These give a very dis¬ 
tinct black cross by polarized light, the intersection 
of the arms of the cross lying on the liilum point. 
In the aggregated granules the cross is not so easily 
visible, as the liilum then lies towards the centre of 
the aggregation, and some care is needful to get out 
the cross by careful rotation of the upper and lower 
prisms as may be required. Taking the starch 
altogether, it will be found to be highly charac¬ 
teristic. 
The resin cells are less regularly shaped than 
those which contain starch. The resinous contents 
are somewhat granular, usually dark in colour, and 
partially soluble in water, which consequently ren¬ 
ders the mass more transparent. Vascular ducts are 
not numerous, and consist of large ‘ barred ’ vessels, 
often perforate in the older laminae. The woody 
fibres are themselves almost ‘ vessels,’ are pitted, 
and do not contain starch, nor usually resin or 
other products. In examining the structure of 
Third Series, No. 103. 
jalap, it will be well to bear in mind that the tubers 
are sometimes exposed to considerable heat in the 
process of drying, and that the form and general 
characters of the starch granules, resin cells, etc., 
are often much modified thereby. 
The adulteration of powdered jalap may be ex¬ 
pected to consist of an admixture with the stems and 
damaged roots of the true jalap and of the substitution 
of or admixture with the powder of Ipomcea Oriza- 
bensis. This may be detected by its greater propor¬ 
tion of w T oody fibre, but more certainly by chemical 
analysis. And, secondly, by admixture of entirely 
foreign matter. ‘ Powder of post ’ is, I think, not so 
commonly used as ten 3 r ears since, but starch of 
various kinds and ground guaiacum cliips are, it is 
said, commonly used still. Of the latter I have no 
personal knowledge, and am inclined to believe that 
the sole commonly current adulterants are starck es 
of potato and arachis, stems oil.purga and damaged 
tubers, and tubers and stems of 1. Orizabensis. The 
starches and stems would be easily recognized by 
aid of the microscope by one familiar with the 
structure of the true tuber, and for the rest recourse 
should be had to chemistry. 
Calumb/E Radix. —The structure of the root of 
this menisperm is very simple, and will not give us 
much trouble. It consists for the most part of 
cellular tissue, with a few vascular vessels, a little 
woody fibre, and a few laticiferous vessels. The 
cells of the parenchyma are somewhat large, with 
very thin walls, very irregular and variable in both 
size and shape. Their contents are large starch 
granules, very variable in size and shape ; sometimes 
single, but generally aggregate. The single ones 
vary in shape from nearly round to mussel-shaped. 
The aggregate granules are usually muller-shaped. 
As might be expected, the form and situation of the 
liilum is as variable as the size of the granule. 
The normal form appears to be a longitudinal furrow, 
but a single point or a 3- or 4-radiate slit or furrow 
are collectively as common. The polarization 
phenomena vary with the shape of the granule and 
situation of the liilum ; but in all the single granules 
a black cross is very marked when the prisms are 
crossed. In the case of the aggregate granules, 
some little care is necessary in order that the cross 
may be seen. This starch, which is, with all its 
variability, characteristic, requires considerable care 
in preparing it for the microscope, owing to the 
great delicacy of the investing membrane of the 
granules. Glycerine jelly with a larger proportion 
of glycerine than usual, or glycerine and gum-water, 
is the best medium in which to mount it per¬ 
manently. 
The pitted vessels are large, by no means numerous 
or regularly distributed, and do not present any 
points of special interest. The woody fibres are ot 
the usual unpitted type. The cells of the cortical 
layer in nowise present marked characters. Special 
canals, composed of short cylindrical cells, occur at 
intervals in the tissue, and contain a yellow-coloured 
substance, probably in chief part calumbine. 
Adulterations of powdered calumba chiefly con¬ 
sist of starches, woody fibre, etc. These would 
be easily detected, as no common starch resembles 
that of calumba; woody fibre in quantity would 
at once betray an adulterant. 
Seneg.e Radix. —The medulla is doubtfully 
present in the majority of specimens. There are 
no medullary rays in the specimens that I have 
