ON THE ANATOMY OV DRUGS. 
545 
opportunities enjoyed by these authors, acts most wisely when he is content to 
be a compiler onl 3 ^ 
As Dr. Berg devotes no less than seven of his quarto plates to the illustration 
of these products, and gives descriptions of the structure of at least fifty varieties 
of bark, it becomes necessary that a somewhat detailed notice should be awarded 
to them. This we should not have been in position to attempt but for the kind¬ 
ness of Mr. Howard, who not only allowed opportunity of reference to the spe¬ 
cimens in his unique collection, but lent his assistance also in the solution of 
many difficulties. 
Firstly, let us award what praise we may to the drawings, as they constitute 
what is in reality the most valuable feature. They are excellent examples of the 
hard, ideal, diagrammatic sort of work before alluded to; too geometrical to be 
entirely natural, but giving, with none the less emphasis on that account, the 
peculiarities of the various sections. 
A transverse section of Cinchona bark shows, at the outer edge, a thin, 
dark, external layer of cork cells, and immediately within it the wider zone 
of obloug, thick-walled cellular tissue, which constitutes the chief portion 
of its substance. This is traversed to a varying extent by long, fibrous liber- 
cells, partially or entirely filled with secondary deposit. In the outer half 
of the zone, these liber-cells are usually absent, whilst in the inner, or part 
nearest the wood, they are often present to such an extent as to form a striking 
feature. It is impossible to define any exact limit between the portion com¬ 
posed entirely of cellular tissue, and that constituting the liber region, but in 
some species an irregular line of laticiferous vessels seems to indicate a sort of 
boundary. The continuation of the medullary rays may often be traced through 
the liber-region till they lose themselves in the outer cellular tissue. A super¬ 
ficial observer might, at first sight, remark a strong resemblance amongst the 
microscopic preparations of the various species, but certain differences depend¬ 
ing on the distribution and arrangement of the structures enumerated, would 
become apparent after a little examination. Whilst some allowance is necessary 
for variations depending on circumstances of growth, we may yet find characters 
of sufficient uniformity for purposes of identification. For instance, in the bark 
of some species of Cinchona, the bast or liber-cells appear in groups; in others 
they occur singly distributed through the parenchyma, or even in radial lines. 
The position and frequency or entire absence of milk-vessels (laticiferous ducts) 
are indications of a certain value. Exceptional characters, such as the presence 
of dark-coloured resin-cells or of crystalline bodies, also yield to the experienced 
observer useful data. It is, however, necessary to guard against the employ¬ 
ment of evidence founded on comparative characters, as though it afforded 
means of absolute diagnosis, and it is here that Dr. Berg has lost his way. The 
table of cinchona barks, classified according to their microscopical appearances, 
which is given as an epitome of the subject, would leave nothing to be desired 
if it were only reliable. We should then be able, from the mere transverse 
section of any bark, to assign it to its proper species on a moment’s examination. 
But, alas, our faith evaporates when w^e find closely allied species, such as C. ovata 
and C. cordifolia, or as C. micrantha and C. nitida^ at opposite ends of the 
series, or when we find species so different in all botanical characters as C. Mr^ 
suta and C. iiitida^ or as C- glandidifera^ C. Calisaya, and C. succiruhra^ placed 
in juxtaposition, and we are forced into the belief that the table is only the 
climax of hair-splitting. Surely a classification, however artificial, should have 
some of the elements of a natural arrangement. 
Mr. Howard pointed out, some years ago, in his‘Nueva Quinologia,’the 
existence in certain barks (that of C. siicciruhra in particular) of stellate groups 
of crystals, consisting of kinovate of quinine, and reverted to the subject at 
greater length in the ‘ Pharmaceutical Journal ’ for May, 1865. These obser- 
