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ON MICROSCOPICAL RESEARCH IN RELATION TO PHARMACY. 233 
out, at any rate with reference to pharmacy. In other branches of science 
more or less connected with medicine the microscope has been extensively 
used, contributing largely to the advances which have been made during re¬ 
cent years in their development, and we may allude especially to Chemistry, 
Materia Medica, and Toxicology, as the medical subjects affecting pharma¬ 
ceutists, which have been participators in the progressive movement. 
In Chemistry proper the use3 which have been made of the instrument 
may be defined under two heads ; firstly, the facility with which minute 
quantities of crystalline bodies may be detected and identified ; and secondly, 
the ease with which the effect of a ray of polarized light passing through a 
body, is observed by its means. The phenomena recently detailed by Mr. 
Tomlinson in his papers on the “ Cohesion Figures of Oils and other Liquids,” 
though often observed with advantage on a small scale by means of magnify¬ 
ing powers, scarcely come^within the range of microscopical research, and be¬ 
long rather to physical than chemical science. 
In a subject like Materia Medica, where the field is so wide and various, 
the microscope has naturally been called into requisition in the investigation 
of numberless obscure and ill-understood points; and much of the value of 
the great work of Dr. Pereira (i. e. so far as the original matter is concerned), 
arises from his extensive knowledge of the instrument and the constant use he 
made of it. Of the advances in knowledge which have been made by its em¬ 
ployment, in the examination of materia medica substances, we need only 
make passing allusion to a few. One of the first of those which strike us is 
that peculiar protean body Starch. We know how readily the starches from 
many plants are now recognized and their origin traced:—the form of the 
granule, its size and physical condition, and its peculiar polarizing properties, 
characters which differ remarkably in the various fseculas used as food, are 
easily observed under high magnifying powers, presenting distinctions of 
which either physician or pharmaceutist may avail himself in the practice of 
his profession, with manifest advantage. Again, the existence of many crys¬ 
talline active principles in crude vegetable products, such as aloine in liquid 
aloes, the cinchona alkaloids in cinchona bark ; of essential oils and resinous 
constituents in the UmbelliferEe, Coniferse, and other Natural Orders of plants ; 
the presence of peculiar inorganic matters, as oxalate of lime raphides in 
Russia or China rhubarb, and in the various products, of the Liliacese, or the 
constant absence of such raphides in the whole Order Umbelliferse,—all of 
these have been made the subjects of more or less successful and valuable 
research. 
The identification of drugs by their microscopical appearance is a process 
so often resorted to that it is needless to enumerate the cases in which it is 
available, and the alterations which occasionally take place in medicinal sub¬ 
stances by the generation of animal and vegetable life have been demon¬ 
strated in a similar manner by Dr. Attfield, Mr. Rimmington, and many other 
observers. 
The investigations made by one of us for the late Dr. Pereira as to the dif¬ 
ferent physical conditions presented by carbonate of magnesia in the light 
and heavy states, are sufficient evidence that in inorganic materia medica the 
same means is equally serviceable in widening our range of knowledge; the 
results obtained in this case affording a beautiful instance of the operation of 
the great law of spherical coalescence, which, since that time, has been so 
ably investigated and laid down by Mr. Rainey in his elaborate researches 
upon organized tissues. 
If the degree of comminution of medicinal powders be a matter of the con¬ 
sequence it is generally supposed to be, nothing but the microscope will assist 
us in its determination. We were recently called upon, in a case of some 
