March 30, 1872.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
7S3 
with and without selenites. (I have, in my paper on 
“ The Optical Examination of Beeswax,” given some 
notes on the use of the polariscope in pharmacy. I 
need not therefore enlarge upon this part of the sub¬ 
ject here, further than to say that, for use in analy¬ 
sis, it is of the first importance that the analysing 
prism should be capable of being rotated.) We 
must see if there be present other secondary cell- 
products, such as crystals or rapliides. If these be 
present, we must ascertain their size, shape, per¬ 
centage to cells, and, if possible, their nature. The 
diagnostic value of these cell-products is often of the 
first importance (hi examination of pulv. rliei, for 
example), AVe should also examine the cells of the 
medulla in the direction of both their long and short 
axis, to see whether their walls be pitted (as in 
elder) or not, and, when pitted, ascertain the nature 
and arrangement of the “ pitting.” This done, we 
shall probably be able to lmow these cells if we meet 
them again. 
We must next attack the vascular sheath of the 
medulla. Is this complete or not ? That is, do the 
vessels of which it is composed encircle the pith, or 
are they (in chicory, for example) in separate wedges? 
Are the vessels wholly spiral ? Are the spirals 
single, double, or even quadruple ? Are they left- or 
right-handed? These questions can be easily an¬ 
swered if their sections be cut in two directions 
(transverse and vertical) with a sharp razor, and 
the vessels teased out by needles. The presence or 
absence of laticiferous vessels, or other receptacula, 
should be ascertained, and, when present, the nature 
of their contents (as hi rheum, glycyrrliiza, etc.). 
The character of the cells forming these receptacula 
is of importance, as in many cases our detection of 
an adulteration (pulv. rliei) depends upon our fami¬ 
liarity with slight variation of these vessels in 
closely allied species of the same genus. Glycerine 
forms the best medium in which specimens of this 
nature can be examined. The woody layers of the 
stem or roots next demand our attention, and require 
its somewdiat prolonged exercise. We notice first 
the arrangement of the medullary cells, their size 
and nature. We ascertain whether they be porous 
or not; wdietlier they have any contents, and, if so, 
their nature, whether organic (starch) or inorganic 
(rapliides or other crystals). We next examine the 
vessels of the woody layers. These are of the most 
varied character, and are usually of the greatest 
diagnostic value. After having noted their distri¬ 
bution through the wood layers, we have to make 
careful longitudinal sections, so as to expose their 
walls for some considerable distance. We shall 
almost invariably find that these vessels are what 
are known as “ dotted ducts,” and not spiral vessels. 
Many of those found hi the examination of pharma¬ 
ceutical specimens are exceedingly interesting. I 
shall describe them in detail by-and-by. The colour 
of these vessels is of some importance, and should be 
noted, as also the nature of their contents, if any. 
The immediately contiguous prosenclivma next 
demands our notice. The character of the secondary 
(sclerogen) deposits, as seen in section, requires to 
be carefully observed. This applies equally to the 
woody tissue properly so called, as these cells (called 
by Dr. Hassall “ stellate cells ”) are often boldly 
characteristic. Secondary cell-contents, when pre¬ 
sent, require to be carefully examined, and their 
nature and quantity determined. 
The bark next comes before us. Here, in addi¬ 
tion to the relative arrangement of its several parts,, 
we have chiefly to concern ourselves with the pre¬ 
sence or absence of inorganic products and of secon¬ 
dary cell-contents in the parenchyma, with the 
length or shortness of the liber-cells, together witlx 
the arrangement of their secondary deposits. 
The examination of an endogenous stem, of a 
conn, bulb, or rhizome, would follow the same ge¬ 
neral rules, each tissue being separately and tho¬ 
roughly examined, and the peculiar features of each 
class of cell entering into its structure accurately' 
ascertained. 
In the examination of seeds, the number of their 
coats should be noted, the nature of the cells com¬ 
posing these, with the character of their contents- 
and secondary deposits. The structure of the seerS 
itself, its receptacula, if any, with the shape and 
properties of its cell-products, require special atten¬ 
tion. In leaves, and foliar organs generally, thg? 
character of the cuticle, number, size and arrange¬ 
ment of stomates and hairs, with characteristics- 
of vessels, cell-contents and deposits, must be ob¬ 
served. To sum up, the work of the analyst in this 
department requires an intimate acquaintance with 
the anatomy of the plant, as does that of the phy ¬ 
sician with the anatomy of the human body. 
After this long, but, it is hoped, not useless digres¬ 
sion, I will return to the detective work in which I 
was engaged. 
(To be continued.) 
PEPSI N. 
A NEW PRACTICAL METHOD TO PREPARE IT J ITS 
PROPERTIES AND DIGESTIVE STRENGTH. 
BY E. SCHEFFER. 
(Continued from page 762.) 
Properties of Acidulated Pepsin. —An acidulated 
solution of pepsin was made, of such strength that 
one fluid ounce contained one grain of purified pep¬ 
sin and two drops of hydrochloric acid, and experi¬ 
mented with. 
By boiling, the clear liquid becomes turbid and 
upon cooling, deposits flakes. 
By addition of alcohol it remains clear at first,, 
but upon standing, flakes of pepsin separate from it. 
Strong hydrochloric acid produces slight turbidity, 
which disappears by addition of more acid or by di¬ 
lution with water. 
Chloride of sodium gives the characteristic pre¬ 
cipitate. 
Bichloride of mercury produces opalescence. 
Tannin forms a heavy precipitate, soluble in hy¬ 
drochloric acid. 
Gallic acid shows no action. 
Carbonate and bicarbonate of soda produce a pre¬ 
cipitate soluble in excess. 
Modified Pepsin. —A solution of carbonate of soda- 
carefully added to a solution of pepsin produces a 
precipitate which, upon being separated from the 
liquid, will prove to be pepsin ; but a little more of 
carbonate of soda will redissolve it again, and the 
liquid no longer contains pepsin; that is, the pepsin 
is destroyed or modified. 
This circumstance caused me to say in my essay 
(American Journal of Pharmacy , 1871, page 6), 
“ dry pepsin, precipitated with alcohol from its sola- 
