ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
387 
Microscopic Characters of Powdered Drugs.* — In discussing the 
botany of the present edition of the British ‘Pharmacopoeia/ in view 
of the approaching revision of that work, Dr. J. Reynolds Green 
says, “In tlio present volume no description is given of the micro- 
scopic characters of powdered drugs. When we consider that in 
the present day most pharmacists purchase many drugs in the con- 
dition of powders, it appears desirable that they should be able to 
identify the powder apart from the drug in the unaltered condition. 
This can be done only by microscopic examination. Many of the con- 
stituents of vegetable tissues have a very definite value in this respect ; 
many starches are extremely distinctive ; the tissues of seeds are very 
unlike those of roots, and so on. It is only necessary here to call atten- 
tion to a few illustrations of this point. Ipecacuanha, when powdered, 
can be recognised with tolerable certainty by two points — the vascular 
elements are in the form of perforated tracheids, true vessels being 
absent ; the starch grains are of a peculiar appearance. Jalap in powder 
again shows distinctive starch grains, peculiar crystals, and numerous 
resin-containing cells. The powdered seeds of strychnos nux vomica 
would be easily identified by the application of the micro-chemical tests 
for brucine and strychnine. 
Many powders need special investigation, of course, to enable accu- 
rate diagnostic tests to be ascertained ; for example, rhubarb, liquorice, 
and gentian powders. A new £ Pharmacopoeia ’ would be much improved 
by the introduction of the distinctive features which such powders pre- 
sent, and these could without much difficulty be determined. Within 
the last ten years much more accurate information has been obtained on 
the point of the definite micro-chemical tests v^hich various constituents 
of vegetable tissues respond to. Those which are given in the present 
‘ Pharmacopoeia ’ are often negative, and some depend on very variable 
constituents. In the case of many decoctions it is stated that they do 
or do not give an indigo-blue colour with iodine. This test is of little 
value as given ; it, of course, is only a test for the presence of starch in 
the drug under discussion. The presence of starch in many roots will 
depend on their condition when gathered ; the quantity of starch, and 
therefore the depth of the colour of the decoction on addition of the 
iodine, will vary very greatly from time to time. In many cases where 
this test was said to give a negative result, the reason for applying it is 
not apparent. The value of the test will depend on its distinguishing 
the drug under examination from another, for which it might be 
mistaken, which does contain starch. In such a case, why should not 
the two drugs be mentioned as differing in this respect ? 
Some of the micro-chemical tests given are not only not distinctive, 
but actually inaccurate. Thus Cusparia bark is said not to give an 
arterial red coloration when the fractured surface is touched with nitric 
acid. In many cases this treatment does produce a red colour, though 
jjerhaps not quite that of arterial blood. Presumably this test is meant 
to distinguish Cusparia bark from that of nux vomica.” 
Intrahydraulic Pressure as a new Method of Investigation.!* — 
Dr. Stanislaus von Stein has constructed an apparatus with which to 
* Brit Med. Journ., No. 1786 (1895) pp. 668-70. 
f Zeitschr. f. wis3. Mikr., xi. (1894) pp. 321-6. 
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