April 20, 1872.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
841 
THE MICROSCOPE IH PHARMACY. 
BY HENRY POCKL1NGTON. 
(<Continued from page 822.) 
Adulterations of, or with, products of Under¬ 
ground Stems. 
Rhei Radix. —The structure of the root of the 
English rhubarb is the easiest to make out. 
Medulla. —Absent or indistinguishable, the centre 
of the root being chiefly occupied by a system of 
dotted vessels. 
Middle zone. —Parenchyma, large, irregular, tliin- 
walled cells, contour of transverse section sinuous, 
and containing great quantities of compound 
starch granules. The compound granule is some¬ 
what oval, and comprises usually four granules, 
each with a distinct liilum, and giving a very distinct 
cross with polarized light; the size of the granules 
is tolerably uniform in any given sample, but varies 
over a few specimens from the same locality very 
considerably. Certain special cells contain large 
aggregate crystals of oxalate of lime (?). The colour¬ 
ing matter and active principle are contained in 
specialized cells, which radiate from the centre out¬ 
wards, and do not seem to have any immediate 
connection with the somewhat limited and very 
irregularly distributed vascular system of dotted 
vessels. 
The structure of Continental rhubarb is closely 
similar to that of English grown, the chief dif¬ 
ference being in the relative proportions of starch, 
crystals and receptacula. The differences between 
the true B. P. rhubarb are in degree rather than in 
kind. 
The old-fashioned Turkey rhubarb is remarkable 
for its paucity of starch, the quantity of crystals, 
the distribution, size, and individuality of its recep¬ 
tacula. 
Indian rhubarb differs from the Turkey in 
having fewer, often very few, crystals, a little more 
starch, and fewer but larger receptacula. As 
“ Turkey ” of the old school is not procurable, the 
tug of war chiefly lies between the true tropical 
varieties and the inferior home or European grown 
ones. 
In the lump the several kinds can be easily 
distinguished. In examining the powder the chief 
questions to be asked are,—Are the starch granules 
numerous in proportion to the rest of the powder; 
if so, are they clearly those of rhubarb ? Are the 
colouring matter receptacula in a fair proportion to 
the particles of fibre, starch and other granules ? 
If so, are they well formed but somewhat irregular, 
moderately-sized single cells, or at most a few 
attached together; or are they (English and Euro¬ 
pean of bad quality) in somewhat long, poverty- 
stricken vessels? The size and number of the 
crystals is a character of some diagnostic impor¬ 
tance ; but it must not be forgotten that English- 
grown rhubarb often contains an extraordinary 
quantity of very large crystals, much more, in fact, 
than even the old Turkey. To sum up. The recep¬ 
tacula in the true B. lb rhubarbs are well-formed, 
individualized cells of moderate size; in English 
and poor European samples are thin, narrow ves¬ 
sels. The rapliides in the true are smaller and 
more elegant crystals, and are not so numerous as 
Third Series, No. 95. 
in English. Starch forms a small proportion in the 
true, a large proportion in the false; the propor¬ 
tion of starch is by far the most important diagnostic 
characteristic. 
Oleum anisi forms the best medium in which to 
immerse the sections of rhubarb root for examina¬ 
tion, and also for the examination of pulvis rhei. 
It the operator can succeed in keeping it in, the 
same medium will answer well for the preserva¬ 
tion of liis specimens; but, although dammar has 
answered well so far, I have doubts whether any 
of the ordinary cements can be depended upon 
for a permanent luting with this medium. On 
account of its high index of refraction and low dis¬ 
persive power, it is invaluable in the examination 
of certain objects. English rhubarb treated with 
it and magnesise carb. levis, strikes an intense rose 
red, these act apparently either upon some matter 
contained within the investing membrane of the 
starch granule, or upon something contained within 
the starch-bearing cells. This reaction is rather 
slow, but is of considerable service. The most com¬ 
mon adulterant of pulv. rhei is, of course, the sub¬ 
stitution of the powder of English grown for that of 
the foreign. Other adulterants are,—Starches, tur¬ 
meric, woody fibres and mineral matter, all of which 
I have frequently found. They are, of course, easily 
recognizable under the microscope, as would be the 
substitution of other roots in powder in company 
with potato starch and turmeric, which a friend tells 
me he has come across, but which I certainly have 
not found, although I have found samples in which 
the rhubarb, or the useful part of it, was in a very 
small minority, and that English. 
Ipecacuanha Radix. —The microscopical charac¬ 
ters are quite as strongly marked as the botanical 
ones. The stem may be divided into two zones, the 
outer and the inner. 
Inner zone. —This may be regarded as the woody 
zone, the medulla being absent. Woody fibres long 
in proportion to their length, large central cavities 
filled with starch corpuscles; walls of wood cells 
much pitted; pits small and irregularly distributed. 
In transverse section these fibres appear as angular 
starch-bearing cells. Starch granules compound, 
2, 4, G, and even more; each with distinct liilum, 
and giving a decided black cross with polarized 
light. Size of granule very variable. Aggregated 
granule muller-sliaped and very variable. 
Outer zone. —Cells much larger, more angular, and 
contain great quantities of starch and some acicular 
rapliides; the latter being very doubly refractive. 
The structure of the external investing membrane is 
not characteristic. The characteristics to be sought 
in the powdered root are, the starch-bearing wood- 
cells, a very infrequent occurrence in other roots, the 
acicular rapliides, and the peculiarly large numbers 
of starch granules aggregated into one starch granule. 
This point will distinguish them from those of maize, 
to which they are otherwise somewhat allied. Of 
the adulterants, chalk may be detected by adding a 
drop of acid at the edge of the thin cover whilst the 
powder is under observation, starches in the usual 
way, woody fibres by their not containing starch, or 
by the absence of the peculiar “pitting” of ipeca¬ 
cuanha wood-cells. 
The structure of “striated ipecacuanha” requires 
study, but must be postponed for consideration in a 
future paper. 
{To be continued.) 
