---------------------------------+----------------+-------------+------
SPECIES (EXCLUDING SUB-SPECIES | | | WHERE
AND VARIETIES) | WHERE FIGURED. | NATIVE | CULTI-
ACCORDING TO WEDDELL. | | COUNTRY. | VATED.
---------------------------------+----------------+-------------+-------
I. Stirps Cinchonæ officinalis | | |
1. Cinchona officinalis Hook |Bot. Mag. 5804 |Ecuador |India,
| | (Loxa) |Ceylon,
| | |Java.
2. ” macrocalyx Pav. |Howard N. Q. |Peru |
| | |
3. ” lucumæfolia Pav. | Do. |Ecuador, |
| |Peru. |
4. ” lanceolata R. et P.(?)| Do. |Peru |
5. ” lancifolia Mutis |Karsten tab. 11.|New Granada |India
| 12.| |
6. ” amygdalifolia Wedd. |Wedd. tab. 6. |Peru, Bolivia|
| | |
II. Stirps Cinchonæ rugosæ | | |
7. Cinchona pitayensis Wedd. |Karst. tab. 22. |New Granada |India
|(C. Trianæ). |(Popayan) |
8. ” rugosa Pav. |Howard N. Q. |Peru |
9. ” Mutisii Lamb. | Do. |Ecuador |
10. ” hirsuta R. et P. |Wedd. tab. 21. |Peru |
11. ” carabayensis Wedd. |Wedd. tab. 19. |Peru, Bolivia|
12. ” Pahudiana How. |Howard N. Q. |Peru |India,
| | |Java
13. ” asperifolia Wedd. |Wedd. tab. 20. |Bolivia |
14. ” umbellulifera Pav. |Howard N. Q. |Peru |
15. ” glandulifera R. et P. | Do. |Peru |
16. ” Humboldtiana Lamb. | Do. |Peru |
| | |
III. Stirps Cinchonæ micranthæ | | |
17. Cinchona australis Wedd. |Wedd. tab. 8. |South Bolivia|
18. ” scrobiculata H. et B. | Do. |Peru |
19. ” peruviana How. |Howard N. Q. |Peru |India
20. ” nitida R. et P. | Do. |Peru |India
21. ” micrantha R. et P. | Do. |Peru |India
| | |
IV. Stirps Cinchonæ Calisayæ | | |
22. Cinchona Calisaya Wedd. |Wedd. tab. 9. |Peru, Bolivia|India,
| | |Ceylon,
| | |Java,
| | |Jamaica,
| | |Mexico.
23. ” elliptica Wedd. | |Peru |
| | (Carabaya) |
| | |
V. Stirps Cinchonæ ovatæ | | |
24. Cinchona purpurea R. et P. |Howard N. Q. |Peru |
| | (Huamalica) |
25. ” rufinervis Wedd. | Do. |Peru, |
| |Bolivia |
26. ” succirubra Pav. | Do. |Ecuador |India,
| | |Ceylon,
| | |Java,
| | |Jamaica.
27. ” ovata R. et P. | Do. |Peru, |India(?),
| |Bolivia |Java(?)
28. ” cordifolia Mutis |Karsten tab. 8. |New Granada, |
| |Peru |
| | |
29. ” tucujensis Karst. |Karsten tab. 9. |Venezuela |
30. ” pubescens Vahl |Wedd. tab. 16. |Ecuador, |
| | Peru, |
| |Bolivia |
| | |
31. ” purpurascens Wedd. |Wedd. tab. 18 |Bolivia |
---------------------------------+----------------+-------------+
---------------------------------+------------------------------------
SPECIES (EXCLUDING SUB-SPECIES |
AND VARIETIES) | PRODUCT
ACCORDING TO WEDDELL. |
---------------------------------+------------------------------------
I. Stirps Cinchonæ officinalis |
1. Cinchona officinalis Hook | Loxa or Crown Bark, Pale Bark.
|
2. ” macrocalyx Pav. | Ashy Crown Bark. The sub-species
| _C. Palton_ affords an important
| sort called _Palton Bark_ much
| used in the manufacture of quinine.
3. ” lucumæfolia Pav. |
|
4. ” lanceolata R. et P.(?)| Carthagena Bark, confounded with
| Palton Bark, but is not so good.
5. ” lancifolia Mutis | Columbian Bark. Imported in large
| quantities for manufacture of
| quinine.The soft Columbian Bark is
| produced by Howard’s var.
| _oblonga_.
|
6. ” amygdalifolia Wedd. | A poor bark, but not now imported.
|
II. Stirps Cinchonæ rugosæ |
7. Cinchona pitayensis Wedd. | Pitayo Bark. Very valuable; used by
| makers of quinine; it is the chief
| source of quinidine.
|
8. ” rugosa Pav. | Bark unknown, probably valueless.
9. ” Mutisii Lamb. | Bark not in commerce, contains only
| aricine.
10. ” hirsuta R. et P. |
11. ” carabayensis Wedd. | Bark not collected.
12. ” Pahudiana How. | A poor bark, yet of handsome
| appearance; propagation of tree
| discontinued.
|
13. ” asperifolia Wedd. | Bark not collected.
14. ” umbellulifera Pav. | Bark not known as a distinct sort.
15. ” glandulifera R. et P. | Do.
16. ” Humboldtiana Lamb. | False Loxa Bark, Jaen Bark. A very
| bad bark.
|
III. Stirps Cinchonæ micranthæ |
17. Cinchona australis Wedd. | An inferior bark, mixed with
| Calisaya.
18. ” scrobiculata H. et B. | Bark formerly known as _Red
| Cusco Bark_ or _Santa Ana Bark_.
19. ” peruviana How. |
20. ” nitida R. et P. | Grey Bark, Huanuco or Lima Bark.
| Chiefly consumed on the Continent.
21. ” micrantha R. et P. |
|
IV. Stirps Cinchonæ Calisayæ |
22. Cinchona Calisaya Wedd. | Calisaya Bark, Bolivian Bark,
| Yellow Bark. The tree exists under
| many varieties, bark also very
| variable.
|
23. ” elliptica Wedd. | Carabaya Bark. Bark scarcely now
| imported. _C. sunsura_ Miq.
| (flower and fruit unknown)
| may perhaps be this species.
|
V. Stirps Cinchonæ ovatæ |
24. Cinchona purpurea R. et P. | Huamalies Bark. Not now Imported.
|
25. ” rufinervis Wedd. | Bark, a kind of light Calisaya.
|
26. ” succirubra Pav. | Red Bark. Largely cultivated in
| British India.
|
27. ” ovata R. et P. | Inferior Brown and Grey Barks.
|
28. ” cordifolia Mutis | Columbian Bark (in part). Tree
| exists under many varieties; bark
| of some used in manufacture of
| quinine.
|
29. ” tucujensis Karst. | Maracaibo Bark.
|
30. ” pubescens Vahl | Arica Bark (Cusco Bark from var.
| _Pelletieriana_). Some of the
| varieties contain aricine.
| _C. caloptera_ Miq. is probably
| a var. of this species.
|
31. ” purpurascens Wedd. | Bark unknown in commerce.
---------------------------------+-----------------------------------------
The liber is traversed by _medullary rays_, which in cinchona are
mostly very obvious, and project more or less distinctly into the
middle cortical tissue. The liber is separated by the medullary rays
into wedges,[1348] which are constituted of a parenchymatous part and
of yellow or orange fibres. The number, colour, shape, and size, but
chiefly the arrangement of these fibres, confer a certain character
common to all the barks of the group under consideration.
The liber-fibres[1349] are elongated and bluntly pointed at their ends,
but never branched, mostly spindle-shaped, straight or slightly curved,
and not exceeding in length 3 millimetres. They are consequently of
a simpler structure than the analogous cells of most other officinal
barks. They are about ¼ to ⅓ mm. thick, their transverse section
exhibiting a quadrangular rather than a circular outline. Their walls
are strongly thickened by numerous secondary deposits, the cavity
being reduced to a narrow cleft, a structure which explains the
brittleness of the fibres. The liber-fibres are either irregularly
scattered in the liber-rays, or they form radial lines transversely
intersected by narrow strips of parenchyme, or they are densely packed
in short bundles. It is a peculiarity of cinchona barks that these
bundles consist always of a few fibres (3 to 5 or 7), whereas in many
other barks (as cinnamon) analogous bundles are made up of a large
number of fibres. Barks provided with long bundles of the latter kind
acquire therefrom a very fibrous fracture, whilst cinchona barks from
their short and simple fibres exhibit a short fracture. It is rather
granular in Calisaya bark, in which the fibres are almost isolated by
parenchymatous tissue. In the bark of _C. scrobiculata_, a somewhat
short fibrous fracture[1350] is due to the arrangement of the fibres
in radial rows. In _C. pubescens_, the fibres are in short bundles and
produce a rather woody fracture.
Besides the liber-fibres, there are some other cells contributing to
the peculiarity of individual cinchona barks. This applies chiefly to
the _laticiferous ducts_ or _vessels_[1351] which are found in many
sorts; they are scattered through the tissue intervening between the
middle cortical layer and the liber, and consist of soft, elongated,
unbranched cells, mostly exceeding in diameter the neighbouring
parenchymatous cells.
As to the _contents of the tissue_ of cinchona barks, crystallized
alkaloids are not visible. Howard has published figures representing
minute rounded aggregations of crystalline matter in the cells, which
he supposes to be kinovates of the alkaloids; and also distinct
acicular crystals which he holds to be of the same nature. These
remarkable appearances are easily observable, yet only after sections
of the bark have been boiled for a minute in weak caustic alkali
and then washed with water; it may well be doubted whether they are
strictly natural. The liquids which are capable of dissolving the
alkaloids in the free state do not afford any if they are applied to
the barks. The alkaloids being contained in the bark in the form of
salts, the latter are decomposed by caustic lye, and the alkaloids set
at liberty assume the crystallized state. This is in our opinion the
origin of the crystals under notice.
[1348] _Baststrahlen_ or _Phloëmstrahlen_ of the Germans.
[1349] _Fibres corticales_ of Weddell; _Baströhren_ or _Bastzellen_ in
German.
[1350] _Fracture filandreuse_, Weddel; _fädiger Bruch_ of the Germans.
[1351] _Vaisseaux laticifères_ of Weddell; _Milchsaftschläuche_ in
German.
The greater number of the parenchymatous cells are loaded with small
starch granules, or in young and fresh barks with chlorophyll. In
several barks, as in that of _C. lancifolia_ Mutis, numerous cells of
the middle cortical layer and even of the medullary rays, are provided
with somewhat thick walls, and contain either a soft brown mass or
crystalline oxalate of calcium. These cells have therefore been called
_resin-cells_ and _crystal-cells_; they are mostly isolated, not
forming extensive groups or zones, and their walls are not strongly
thickened as in true sclerenchymatous tissue. If thin sections of
the barks are moistened with dilute alcoholic perchloride of iron,
the walls of the cells, except the fibres and the cork, assume a
blackish-green due to cincho-tannic acid; this applies even to the
starch granules.
_Characters of particular sorts._—The modifications of general
structure just described, are sufficient to impart a special character
to the bark of many species of Cinchona, provided the bark is examined
at its full development, the structural peculiarities being far from
well-marked in young barks.
Thus it is not possible to point out any distinctive features for
the _Loxa Bark_ of commerce, because it is mostly taken from young
wood. We may say of it, that neither resin-cells nor crystal-cells
occur in its middle layer, that its laticiferous vessels become soon
obliterated, and have indeed disappeared in the older quills; and that
the liber-fibres form interrupted, not very regular, radial rows.
The quills of _C. Calisaya_ display large laticiferous ducts, which
are wanting in the flat bark. There is a peculiar sort of the latter
called _Bolivian Calisaya_ (already mentioned at p. 353), the flat
pieces of which still possess very obvious laticiferous vessels. As to
the liber-fibres of Calisaya bark, they are, as before stated (p. 356),
scattered throughout the parenchymatous tissue or endophlœum. In the
bark of _C. scrobiculata_, which might at first sight be confounded
with Calisaya bark, the liber-fibres form radial, less interrupted
rows. The microscope affords therefore the means of distinguishing
these two barks.
The barks of _C. succirubra_ are particularly rich in laticiferous
ducts, mostly of considerable diameter, in which the formation of new
parenchyme may not unfrequently be observed. The orange liber-fibres
occurring in this bark are less numerous, more scattered, and of
smaller size than in Calisaya. The fracture of Red Bark, especially the
flat sort, is therefore more finely granular and not so coarse as that
of Calisaya.
The structural characters of Cinchona barks may lastly be fully
appreciated by examining barks of the allied genera _Buena_,
_Cascarilla_ and _Ladenbergia_, which were formerly known under
the name of _False Cinchona Barks_. The microscope shows that the
liber-fibres of the latter are soft, branched and long, densely
packed into large bundles, imparting therefore a well-marked fibrous
structure. The external appearance of these barks is widely different
from that of true cinchona barks; none of them it would appear is now
collected for the purpose of adulteration.
=Chemical Composition=—The most important and at the same time
peculiar principles of Cinchona bark are the _Alkaloids_,—enumerated in
the following table:—[1352]
Cinchonine C₂₀H₂₄N₂O.
or, as proposed by Skraup (1878) C₁₉H₂₂N₂O.
Cinchonidine (_Quinidine_ of many writers) same formula.
Quinine C₂₀H₂₄N₂O₂.
Quinidine (_Conquinine_ of Hesse) same formula.
Quinamine C₁₉H₂₄N₂O₂.
Conquinamine (_Conchinamine_) same formula.
B. A. Gomes[1353] of Lisbon (1810) first succeeded in obtaining active
principles of cinchona, by treating an alcoholic extract of the bark
with water, adding to the solution caustic potash, and crystallizing
the precipitate from alcohol. The basic properties of the substance
thus obtained, which Gomes called _Cinchonino_, were observed in the
laboratory of Thénard by Houtou-Labillardière, and communicated to
Pelletier and Caventou.[1354] Shortly before that time, Sertürner had
asserted the existence of organic alkalis: and the French chemists,
guided by that brilliant discovery, were enabled to show that the
_Cinchonino_ of Gomes belonged to the same class of substances.
Pelletier and Caventou, however, speedily pointed out that it consisted
of two distinct alkaloids, one of which they named _Quinine_, the
other _Cinchonine_. In 1827 the Institut de France awarded to the two
chemists for their discovery the Montyon prize of 10,000 francs (see
page 57, note 4).
[1352] Hesse, in 1877, pointed out the existence of a series of
new alkaloids existing in Cinchona. We refrain from repeating his
statements, which will be found abstracted in the _Yearbook of Pharm._
1878. 63.
[1353] Ensaio sobre o Cinchonino, e sobre sua influencia na virtude da
quina e d’outras cascas.—_Mem. da Acad. R. das Sciencias de Lisboa_,
iii. (1812) 202-217.
[1354] _Ann. de Chim. et de Phys._ xv. (1820) 292.
_Cinchonidine_ (thus called by Pasteur in 1853) was first obtained and
characterized under the name of _Quinidine_ in 1847, by F. L. Winckler
of Darmstadt, from Maracaibo Bark (_C. tucujensis_ Karst.); and in
1852 it was more closely studied by Leers, still under the name of
_quinidine_.
_Cinchovatine_, formerly stated to be a peculiar alkaloid, has been
shown by Hesse in 1876 to agree with cinchonidine.
_Quinidine_ is the name applied by Henry and Delondre to an alkaloid
they obtained in 1833; its peculiar nature was not clearly proved
until 1853, when Pasteur examined it, and 1857 when De Vry showed its
identity with the _Beta-quinine_ extracted in 1849 by Van Heijningnen
from commercial quinoidin. The name _quinidine_ having been since
applied to different basic substances more or less pure, Hesse (1865)
has proposed to replace it by that of _Conquinine_ (Conchinin in
German). The alkaloid is especially characteristic of the Pitayo barks,
and also occurs in the Calisaya barks from Java.
_Quinamine_ was discovered in 1872 by Hesse, in bark of _C. succirubra_
cultivated at Darjiling in British Sikkim; it is also of common
occurrence in the barks collected in Java. _Conquinamine_ was extracted
in 1873 by Hesse from old barks from British India.
_Paricine_ is another basic substance discovered in 1845 by Winckler,
in the bark of _Buena hexandra_ Pohl. Hesse detected it along with
quinamine in the bark of _C. succirubra_; its composition is not yet
known.
_Aricine_, C₂₃H₂₆N₂O₄, and _Cusconine_, C₂₃H₂₆N₂O₄ + 2 OH₂, occur in
the so-called false Cinchona barks of not ascertained botanic origin.
These alkaloids differ in many respects from those of true Cinchona
barks.[1355]
_Pitoyine_ was pointed out by Peretti (1837), but Hesse has shown
(1873) that the bark called _China bicolorata Tecamez_[1356] or _Pitoya
Bark_ from which it was obtained, is altogether destitute of alkaloid.
Lastly may be mentioned _Paytine_, C₂₁H₂₄N₂O + OH₂, a crystallizable
alkaloid discovered in 1870 by Hesse in a white bark of uncertain
origin.[1357] It is allied to quinamine and quinidine, but has not been
met with in any known cinchona bark.
By heating for a length of time solutions of the cinchona alkaloids
with an excess of some mineral acid, Pasteur (1753) obtained amorphous
modifications of the natural bases. Quinine thus afforded _Quinicine_,
having the same composition; cinchonine and cinchonidine furnished
_Cinchonicine_, likewise agreeing in composition with the alkaloids
from which it originates. These amorphous products may also be obtained
by heating the natural bases in glycerin at 200° C., when a red
substance is also formed. In quinine manufactories, amorphous alkaloids
are constantly met with, being partly produced in the course of the
manipulations to which the materials are subjected. Yet cinchona barks
also afford _amorphous alkaloids_ at the very outset of analysis,
whence we must infer their existence in the living plant.
The name _Quinoidine_ (or rather “_Chinioïdin_”) was applied by
Sertürner (1829) to an uncrystallizable basic substance, which he
prepared from cinchona barks, and found to be a peculiar alkaloid. The
term has subsequently been bestowed upon a preparation which has found
its way into commerce and medical practice, in the form of a dark brown
brittle extractiform mass, softening below 100° C., and having usually
a slight alkaline reaction. It is obtained in quinine factories by
precipitating the brown mother-liquors with ammonia, and contains the
amorphous alkaloids naturally occurring in the barks. Quinoidin should
not be used unless, when previously dried at 100°, it proves to afford
at least 70 per cent. of alkaloids soluble in ether.
Quinine and the allied alkaloids have not been met with in any
appreciable amount in other parts of the cinchonas than the bark, nor
has their presence been ascertained in other plants than those of the
tribe _Cinchoneæ_.
[1355] _Yearbook of Pharm._ 1878. 59.
[1356] So called from Tecamez or Tacames, a small port of Ecuador
in about lat. 1° N. The bark which was first noticed in Lambert’s
_Description of the Genus Cinchona_, 1797. 30. tab. ii., is of unknown
botanical origin. In its external appearance, as well as in its
structure, this bark is widely different from any Cinchona bark.—See
also Vogl, in the second pamphlet quoted at page 391. 10; Oberlin and
Schlagdenhauffen, _Journ. de Pharm._ 28. (1878) 252.
[1357] Flückiger in Wiggers and Husemann, _Jahresbericht_ for 1872. 132.
Characters of the Cinchona Alkaloids.
1. _Quinine._—It is obtained from alcoholic solutions, in prisms of
the composition C₂₀H₂₄N₂O₂ + 3 OH₂, fusing at 57° C. The crystals may
be deprived of water by warming or exposure over oil of vitriol, and
they fuse at 177° C. The anhydrous alkaloid is likewise crystallizable;
it requires about 21 parts of ether for solution, but dissolves more
readily in chloroform or absolute alcohol. These solutions deviate the
ray of polarized light to the left, and so do likewise solutions of the
salts of quinine. Yet one and the same quantity of alkaloid exhibits
a very different rotatory power according to the solvent used, though
the volume of the solution remain the same. Even the common sulphate
differs in this respect from the two other sulphates of quinine. The
same remark applies to the optical power of the other alkaloids.
If ten volumes of a solution of quinine, or of one of its salts, are
mixed in a test tube with one volume of chlorine water, and a drop
of ammonia is added, a brilliant green colour makes its appearance.
In solutions rich in quinine, a green precipitate, _Thalleioquin_ or
_Dalleiochine_ is produced; in solutions containing less than ¹/₁₀₀₀
of quinine, no precipitate is formed, but the fluid assumes a green
even more beautiful than in a stronger solution. The test succeeds
with a solution containing only one part of quinine in 5,000, and in a
solution containing not more than ¹/₂₀₀₀ of quinine, if bromine is used
instead of chlorine.[1358]
The bitter taste of quinine is not appreciable in solutions containing
less than one part in 100,000. The blue fluorescence displayed by a
solution of quinine in dilute sulphuric acid is observable in solutions
containing much less than one part in 200,000 of water; yet it is not
apparent in very strong solutions.
Besides the _common medicinal_ sulphate, 2 C₂₀H₂₄N₂O₂ + SO₄H₂ + 8 OH₂,
quinine forms two other crystallizable sulphates, namely the sulphate,
C₂₀H₂₄N₂O₂ + SO₄H₂ + 7 OH₂, and a third having the composition
C₂₀H₂₄N₂O₂ + 2 SO₄H₂ + 7 OH₂.
Herapath, at Bristol, showed in 1852 that quinine forms with sulphuric
acid and iodine a peculiar compound, _Iodo-sulphate of Quinine_,
having the composition (C₂₀H₂₄N₂O₂)₄ + 3 (SO₄H₂) + 2 HI + 4 I + 3
OH₂. As this substance possesses optical properties analogous to
those of tourmaline, it was called by Haidinger, _Herapathite_. It
may be easily obtained by dissolving sulphate of quinine in 10 parts
of weak spirit of wine containing 5 per cent. of sulphuric acid, and
adding an alcoholic solution of iodine until a black precipitate is no
longer formed. This precipitate is collected on a filter and washed
with alcohol; then dissolved in boiling spirit of wine and allowed
to crystallize. The tabular crystals thus obtained are extremely
remarkable on account of their dichroism and polarizing power, as well
as for the sparing solubility, since they require 1000 parts of boiling
water for solution; their sparing solubility in cold alcohol may be
utilized for separating quinine from the other cinchona alkaloids and
estimating its quantity.
2. _Quinidine_ or _Conquinine_—forms crystals having the composition,
C₂₀H₂₄N₂O₂ + 2 OH₂; the anhydrous alkaloid melts at 168° C., and
requires about 30 parts of ether for solution. Its solutions are
strongly dextrogyre; it agrees with quinine as regards bitterness,
fluorescence and the thalleioquin test, and forms a neutral and an
acid sulphate. The most striking character of quinidine is afforded by
its hydriodate, the crystals of which require for solution at 15° C.,
1250 parts of water or 110 parts of alcohol sp. gr. ·834. Quinidine
may therefore be separated from the other alkaloids of bark by a
solution of iodide of potassium which will precipitate the hydriodate.
According to Hesse (1873), quinidine is further characterized by the
fact that its sulphate is soluble in 20 parts of chloroform at 15° C.,
the sulphates of the other cinchona alkaloids being far less soluble in
that liquid. The common medicinal sulphate of quinine, _e.g._, requires
for solution 1000 parts of chloroform.
[1358] _Pharm. Journ._, May 11, 1872. 901.
3. _Cinchonine._—This alkaloid forms crystals which are always
anhydrous; they fuse at 257° C., and require about 400 parts of ether
and 120 of spirit of wine for solution. Cinchonine further differs from
quinine by its dextrogyre power, its want of fluorescence, and its
non-susceptibility to the thalleioquin test. Its hydriodate is readily
soluble in water, and still more so in alcohol whether dilute or strong.
4. _Cinchonidine._—forms anhydrous crystals melting at 206° C., soluble
in 76 parts of ether, or 20 of spirit of wine, then affording levogyre
liquids, devoid of fluorescence, and not acquiring a green colour
(thalleioquin) by means of chlorine water and ammonia. Hydrochlorate of
cinchonidine forms pyramidal crystals of the monoclinic system, very
different from the hydrochlorates of the allied alkaloids.
5. _Quinamine._—The crystals are anhydrous, fuse at 172° C., and form
at a temp. of 20°, with 32 parts of ether or 100 parts of spirit of
wine, a dextrogyre solution. Quinamine is even to some extent soluble
in boiling water, and abundantly in boiling ether, benzol, or petroleum
ether. The solutions of quinamine do not stand the thalleioquin test,
nor do they display fluorescence; in acid solution, the alkaloid
is liable to be transformed into an amorphous state. Quinamine
moistened with concentrated nitric acid, assumes like paytine a yellow
coloration. Its hydriodate is readily soluble in boiling water, but
very sparingly in cold water, especially in presence of iodide of
potassium, in which respect it is allied to quinidine as well as to
paytine.
The more important properties of the Cinchona alkaloids may be
summarized as follows:—
a. _Hydrated_ crystals are formed by
Quinine, Quinidine, (or Conquinine).
_No hydrated_ crystals by
Cinchonine, Cinchonidine, Quinamine.
b. _Abundantly_ soluble in ether
Quinine, Quinidine, Quinamine,
and the amorphous alkaloids.
_Sparingly_ soluble in ether Cinchonidine.
_Almost insoluble_ in ether Cinchonine.
c. _Levogyre_ solutions afforded by
Quinine, Cinchonidine.
_Dextrogyre_ solutions by
Cinchonine, Quinidine, Quinamine,
Conquinamine, and the amorphous alkaloids.
d. Thalleioquin is formed by
Quinine, Quinidine, and also by Quinicine.
Thalleioquin cannot be obtained from
Cinchonine, Cinchonidine, Quinamine,
nor from Cinchonicine.
e. Fluorescence is displayed by solutions of Quinine, Quinidine.
No fluorescence in solutions of pure Cinchonine, Cinchonidine,
Quinamine.
=Proportion of Alkaloids in Cinchona Barks=—This is liable to very
great variation. We know from the experiments of Hesse (1871), that
the bark of _C. pubescens_ Vahl is sometimes devoid of alkaloid.[1359]
Similar observations made near Bogota upon _C. pitayensis_ Wedd., _C.
corymbosa_ Karst., and _C. lancifolia_ Mutis, are due to Karsten. He
ascertained[1360] that barks of one district were sometimes devoid of
quinine, while those of the same species from a neighbouring locality
yielded 3½ to 4½ per cent. of sulphate of quinine.
[1359] _Berichte der Deutschen Chem. Gesellschaft zu Berlin_, 1871. 818.
[1360] _Die medicinischen Chinarinden Neu-Granada’s_, 17. 20. 39.
Another striking example is furnished by De Vry[1361] in his
examination of quills of _C. officinalis_ grown at Ootacamund, which
he found to vary in percentage of alkaloids, from 11·96 (of which 9·1
per cent. was quinine) down to less than 1 per cent. An extremely
remarkable variation has also been displayed, as already alluded to at
p. 351, by Ledger’s Calisaya.
Among the innumerable published analyses of cinchona bark, there
are a great number showing but a very small percentage of the
useful principles, of which quinine, the most valuable of all, is
not seldom altogether wanting. The highest yield on the other hand
hitherto observed, was obtained by Broughton[1362] from a bark grown
at Ootacamund. This bark afforded not less than 13½ per cent. of
alkaloids, among which quinine was predominant. In Java too, Cinchona
Ledgeriana (see pp. 341, 351) has proved since to afford much more
alkaloid than any American barks; as much as 13·25 per cent. of quinine
have been observed in its bark.
The few facts just mentioned show that it is impossible to state even
approximately any constant percentage of alkaloids in any given bark.
We may however say that good _Flat Calisaya Bark_, as offered in the
drug trade for pharmaceutical preparations, contains at least 5 to 6
per cent. of quinine.
As to _Crown_ or _Loxa Bark_, the _Cortex Cinchonæ pallidæ_ of
pharmacy, its merits are, to say the least, very uncertain. On its
first introduction in the 17th century, when it was taken from the
trunks and large branches of full-grown trees, it was doubtless an
excellent medicinal bark; but the same cannot be said of much of that
now found in commerce, which is to a large extent collected from very
young wood.[1363] Some of the Crown Bark produced in India is however
of extraordinary excellence, as shown by the recent experiments of De
Vry.[1364]
As to _Red Bark_, the thick flat sort contains only 3 to 4 per cent. of
alkaloids, but a large amount of coloring matter. The quill Red Bark of
the Indian plantations is a much better drug, some of it yielding 5 to
10 per cent. of alkaloids, less than a third of which is quinine and a
fourth cinchonidine, the remainder being cinchonine and sometimes also
traces of quinidine (conquinine).
The variations in the amount of alkaloids relates not merely to their
total percentage, but also to the proportion which one bears to
another. Quinine and cinchonine are of the most frequent occurrence;
cinchonidine is less usual, while quinidine is still less frequently
met with and never in large amount. The experiments performed in
India[1365] have already shown that external influences contribute in
an important manner to the formation of this or that alkaloid; and
it may even be hoped that the cultivators of cinchona will discover
methods of promoting the formation of quinine and of reducing, if not
of excluding, that of the less valuable alkaloids.
[1361] _Pharm. Journ._ Sept. 6, 1873. 181.
[1362] Blue Book—“_East India Chinchona Plant_,” 1870. 282; _Yearbook
of Pharmacy_, 1871. 85.
[1363] See Howard’s analyses and observations, _Pharm. Journ._ xiv.
(1855) 61-63.
[1364] _Pharm. Journ._ Sept. 6, 1873. 184.
[1365] Blue Book, 1870. 116. 188. 205.
Most salts of the alkaloids of cinchona afford a beautiful purple tar
when they are heated in a test tube, and the same is also produced with
the powdered bark, provided alkaloids be present. No other bark, as
far as we know, yields a similar product of the dry distillation. It
is not observed even in using true Cinchona barks, which are devoid of
alkaloids. This method for ascertaining the presence of alkaloids in
Cinchona barks has been proposed in 1858 by Grahe of Kasan. Hesse has
improved Grahe’s test in the following way: he extracts the powdered
bark with slightly acidulated water and dries up the liquid with a
little of the powder. _Grahe’s test_ at once shows whether a given bark
contains Cinchona alkaloids or not.
=Acid principles of Cinchona Barks=—Count Claude de la Garaye[1366]
observed (1746) a crystalline salt deposited in extract of cinchona
bark, which salt was known for some time in France as _Sel essential
de la Garaye_. Hermbstädt at Berlin (1785) showed it to be a salt of
calcium, the peculiarity of whose acid was pointed out in 1790 by
C. A. Hoffmann,[1367] an apothecary of Leer in Hanover, who termed
it _Chinasäure_. The composition of this substance, which is the
_Kinic Acid_ of English chemists, was ascertained by Liebig in 1830
to be C₇H₁₂O₆, or now C₆H₇(OH)₄COOH. The acid forms large monoclinic
prisms, fusible at 162° C., of a strong and pure acid taste, soluble
in two parts of water, also in spirit of wine, but hardly in ether.
The solutions are levogyre. Kinic acid appears to be present in every
species, and also to occur in barks of allied genera; and in fact to
be of somewhat wide distribution in the vegetable kingdom. By heating
it or a kinate, interesting derivatives are obtained; thus, by means
of peroxide of manganese and sulphuric acid, we get yellow crystals
of _Kinone_ or _Quinone_, C₆H₄O₂,—a reaction which may be used for
ascertaining the presence of kinic acid. Kinic acid is devoid of any
noteworthy physiological action.
_Cincho-tannic Acid_—is precipitated from a decoction of bark by
acetate of lead, after the decoction has been freed from cinchona-red
by means of magnesia. Dr. de Vry informed us that the Indian barks
are usually richer in cincho-tannic acid; their cold infusion becomes
turbid on addition of hydrochloric acid, which forms an insoluble
compound with the former.
The cincho-tannate of lead decomposed by sulphuretted hydrogen, and
the solution cautiously evaporated _in vacuo_, yields the acid as an
amorphous, hygroscopic substance, readily soluble in water, alcohol, or
ether. The solutions, especially in presence of an alkali, are quickly
decomposed, a red flocculent matter, _Cinchona-red_, being produced.
Solutions of cincho-tannic acid assume a greenish colour on addition of
a ferric salt. By destructive distillation, cincho-tannic acid affords
pyrocatechin.
_Quinovic_ (or _Chinovic_) _Acid_, C₂₄H₃₈O₄, crystallizes in hexagonal
scales which are sparingly soluble in cold alcohol, more readily in
boiling alcohol, but not dissolved by water, ether, or chloroform. It
occurs in cinchona barks, and has been met with by Rembold (1868) in
the rhizome of _Potentilla Tormentilla_ Sibth.
[1366] _Chimie hydraulique_, Paris, 1746. 114.
[1367] Crell’s _Chem. Annalen_, 1790, ii. 314-317.
=Other Constituents of Cinchona Barks=—Quinovic acid is accompanied by
_Quinovin_ (or _Chinovin_), C₃₀H₄₈O₈, an amorphous bitter substance,
first obtained (1821) by Pelletier and Caventou under the name of
_Kinovic Acid_, from _China nova_,[1368] in which it occurs combined
with lime. Quinovin in alcoholic solution was shown in 1859 by
Hlasiwetz to be resolved by means of hydrochloric gas into quinovic
acid, C₂₄H₃₈O₄, and an uncrystallizable sugar, _Mannitan_, C₆H₁₂O₅,
with subtraction of H₂O. The formation of quinovic acid takes place
more easily, if quinovin is placed in contact with sodium amalgam and
spirit of wine, when, after 12 hours, mannitan and quinovate of sodium
are formed (Rochleder, 1867).
Quinovin, although an indifferent substance, may be removed from
cinchona barks by weak caustic soda, from which it is precipitable by
hydrochloric acid, together with quinovic acid and cinchona-red. Milk
of lime then dissolves quinovin and quinovic acid, but not the red
substance. Quinovic acid and quinovin again precipitated by an acid,
may be separated by chloroform in which the latter only is soluble, or
also by cold dilute alcohol sp. gr. about 0·926, quinovin being readily
removed by this liquid.
Quinovin dissolves in boiling water; its solutions, as well as those of
quinovic acid, are dextrogyre. Quinovin seems to be a constituent of
almost every part of the cinchonas and the allied _Cinchoneæ_, although
the amount of it in barks does not apparently exceed 2 per cent. It is
accompanied by quinovic acid: both substances are stated to have tonic
properties.
_Cinchona-red_, an amorphous substance to which the red hue of
cinchona barks is due, is produced as shown by Rembold (1867), when
cincho-tannic acid is boiled with dilute sulphuric acid, sugar
being formed at the same time. By fusing cinchona-red with potash,
protocatechuic acid, C₇H₆O₄, is produced. Cinchona-red is sparingly
soluble in alcohol, abundantly in alkaline solutions, but neither in
water nor in ether. Thick Red Bark in which it is abundant, affords it
to the extent of over 10 per cent.
The Cinchona barks yield but a scanty percentage of ash, not exceeding
3 per cent., a fact well according with the small amount they contain
of oxalate and kinate of calcium.
=Estimation of the Alkaloids in Cinchona Bark=—The microscope will
enable us, as already shown, to ascertain whether a given bark is
derived from _Cinchona_, but it can furnish no exact information as to
the actual value of such bark as a drug.
Yet there is a very simple test by which the presence of a
cinchona-alkaloid may be demonstrated. These alkaloids heated in a
glass tube in the presence of a volatile acid or of substances capable
of producing a volatile acid, evolve heavy vapours of a beautiful
crimson colour, as mentioned p. 363.
[1368] The bark of _Buena magnifolia_ Wedd., a tree with fragrant
flowers and magnificent foliage, figured in Howard’s “_Nueva Quinologia
of Pavon_” as Cinchona magnifolia. Its bark is destitute of alkaloids;
it also used to appear occasionally in the London market since about
the year 1820.—See also our article on _Cortex Cascarillæ_.
But to ascertain the real value of a cinchona bark, a quantitative
estimation of the alkaloids is necessary. A good process for this
operation has been given by De Vry.[1369] It is as follows:—Mix 20
grammes of powdered bark, dried at 100° C., with milk of lime (5 grm.
slaked lime to 50 grm. water), dry the mixture slowly; by stirring
it frequently, the cincho-tannic acid loses its solubility, being
gradually transformed into cinchona-red. Then boil the dry powder with
200 cubic centimetres of alcohol 0·830 sp. gr. Pour the liquid on to a
small filter, and afterwards the residual bark and lime mixed with 100
cub. cent. more alcohol. Wash the powder on the filter with 100 cub.
cent. of spirit From the mixed liquids, about 370 cub. cent., separate
the calcium by a few drops of weak sulphuric acid. Filter, distill off
the spirit and pour into a capsule the residual liquid,—to which add a
small quantity of spirit and water with which the distilling apparatus
has been rinsed out. Let the capsule be now heated on a water-bath
until all the spirit shall have been expelled; and let the remaining
liquor which contains all the alkaloids in the form of acid sulphates
be filtered. There will remain on the filter quinovic acid and fatty
substances, which must be washed with slightly acidulated water. The
filtrate and washings reduced to about 50 cub. cent., should be treated
while still warm with caustic soda in excess. After cooling, this is
decanted off from the precipitate, and then water added to it before
throwing it on to a filter. It is then to be washed with the smallest
quantity of water pressed between folds of blotting paper, removed
therefrom and dried. The weight multiplied by 5 will indicate the
percentage of _mixed_ alkaloids in the bark.
[1369] _Pharm. Journ._ iv. (1873) 241, and Dr. de Vry’s papers
mentioned at the end of the present article, p. 369; also private
communications.
To separate the alkaloids from each other, treat the powdered mass
with ten times its weight of ether. This will resolve it into two
portions—(a) _insoluble in ether_, (b) _soluble in ether_.
(a.) This should be converted into neutral acetates, and to the
solution there should be added iodide of potassium, which will possibly
separate a little _quinidine_. After removal of the latter (if
present), add solution of tartrate of potassium and sodium, which will
throw down in a crystalline form tartrate of _cinchonidine_; from the
mother-liquor, _cinchonine_ may be precipitated by caustic soda.
(b.) The ether having been evaporated, the residue is to be dried at
100° C. and weighed. It may in many cases practically be considered
as consisting of quinine only. If however the estimation of quinidine
(conquinine) and quinamine is required, the residue, or a determined
portion of it, should be dissolved in acetic acid just as much as
will be necessary for affording a neutral solution. From this the
hydroiodate of quinidine is precipitated by means of an alcoholic
solution of iodide of potassium. In the filtrate quinine may be
precipitated by adding a few drops of dilute sulphuric acid and an
alcoholic tincture of iodine. The herapathite thus formed (see p. 360)
is collected after a day, dried at 100° and weighed; it then contains
55 per cent. of quinine.
After adding a few drops of sulphurous acid, the alcohol should now be
evaporated from the fluid from which the crystals of herapathite have
been removed, and caustic lye added, by which the amorphous alkaloids
will be precipitated, including _quinamine_ if present.
=Uses=—Cinchona bark enjoys the reputation of being a most valuable
remedy in fevers. But the uncertainty of its composition and its
inconvenient bulk render it a far less eligible form of medicine than
the alkaloids themselves. It is nevertheless much used as a general
tonic in various pharmaceutical preparations.
As to the alkaloids, the only one which is in general use is _quinine_.
The neglect of the others is a regrettable waste, which the result of
recent investigations ought to obviate. In the year 1866 the Madras
Government appointed a Medical Commission to test the respective
efficacy in the treatment of fever, of Quinine, Quinidine, Cinchonine
and Cinchonidine. Of the sulphates of these alkaloids, a due supply,
specially prepared under Mr. Howard’s superintendence, was placed
at the disposal of the Commission. From the report[1370] it appears
that the number of cases of paroxysmal malarious fevers treated was
2472,—namely 846 with Quinine, 664 with Quinidine, 569 with Cinchonine,
and 403 with Cinchonidine. Of these 2472 cases, 2445 were cured, and
27 failed. The difference in remedial value of the four alkaloids, as
deduced from these experiments, may be thus stated:—
Quinidine—ratio of failure per 1000 cases treated 6
Quinine ” ” 7
Cinchonidine ” ” 10
Cinchonine ” ” 23
The Indian Government, acting on the recommendation of Mr. Howard,
has officially advised (Dec. 16, 1873) the more free use India of
cinchona alkaloids other than quinine, and especially of _sulphate of
cinchonidine_, which is procurable in abundance from Red Bark.[1371]
Quinidine on the other hand, which has proved the most valuable of all,
is only obtainable from a few barks and in very limited amount.
Dr. de Vry since 1876 advocates the use of what he calls _Quinetum_.
This preparation is obtained by exhausting the barks with slightly
acidulated water, and precipitating the whole amount of alkaloids by
caustic soda. In India the remedy is known as “the Febrifuge.”[1372]
=Adulteration=—There is not now any frequent importation of _spurious_
cinchona barks, but the substitution of bad varieties for good is
sufficiently common. To discriminate these in a positive manner by
ascertaining the percentage of quinine, which is the chief criterion
of value, recourse must be had to chemical analysis, a method of
performing which has been described. Entirely worthless barks may be
easily recognized by means of Grahe’s test (p. 363).
[1370] Blue Book—_East India Cinchona Cultivation_, 1870. pp.
156-172.—The report contains very interesting and important medical
details. See also Dougal in _Edin. Med. Journ._ Sept. 1873.
[1371] We heard that the Government has purchased (April 1874) by
tender between 300 and 400 lb. of cinchonidine.
[1372] _Pharm. Journ._ viii. (1878) 1060.
Modern Works relating to Cinchona.
The following enumeration has been drawn up for the sake of those
desiring more ample information than is contained in the foregoing
pages, but it has no pretension to be a complete list of all
publications that have lately appeared on the subject.
Berg (Otto), _Chinarinden der pharmakognostischen Sammlung
zu Berlin_. Berlin, 1865, 4°. 48 pages and 10 plates
showing the microscopic structure of barks.
Bergen (Heinrich von), _Monographie der China_.
Hamburg, 1826, 4°. 348 pages and 7 coloured plates
representing the following barks:—China rubra, Huanuco,
Calisaya, flava, Huamalies, Loxa, Jaen. An exhaustive
work for its period in every direction.
Blue books—_East India_ (_Chinchona Plant_). Folio.
=a.= _Copy of Correspondence relating to the
introduction of the Chinchona Plant into India, and
to proceedings connected with its cultivation from
March 1852 to March 1863._ Ordered by the House of
Commons to be printed, 20 March 1863. 272 pages.
Contains Correspondence of Royle, Markham, Spruce,
Pritchett, Cross, McIvor, Andersen and others,
illustrated by 5 maps.
=b.= _Copy of further Correspondence relating to
the introduction of the Chinchona Plant into India,
and to proceedings connected with its cultivation,
from April 1863 to April 1866._ Ordered by the
House of Commons to be printed, 18 June 1866. 379
pages.
Contains Monthly Reports of the plantations on the
Neilgherry Hills; Annual Reports for 1863-64, 1864-65,
with details of method of propagation and cultivation,
barking, mossing, attacks of insects, illustrated by
woodcuts and 4 plates; report of Cross’s journey to
Pitayo, with map; Cinchona cultivation in Wynaad,
Coorg, the Pulney Hills and Travancore, with map;
in British Sikkim, the Kangra, Valley (Punjab), the
Bombay Presidency, and Ceylon.
=c.= _Copy of all Correspondence between the
Secretary of State for India and the Governor-General,
and the Governors of Madras and Bombay, relating to
the cultivation of Chinchona Plants, from April 1866
to April 1870._ Ordered by the House of Commons to
be printed, 9 August 1870. 285 pages.
Contains reports on the Neilgherry and other plantations,
with map; appointment of Mr. Broughton as analytical
chemist, his reports and analyses; reports on the
relative efficacy of the several cinchona alkaloids,
on cinchona cultivation at Darjiling and in British Burma.
=d.= _Copies of the Chinchona Correspondence (in
continuation of return of 1870), from August 1870 to
July 1875._ Ordered by the House of Commons to be
printed, 21 June 1877. 190 pages.
Contain also reports on the alkaloid manufactory in India,
collection and shipment of barks, and analyses of barks.
Delondre (Augustin Pierre) et Bouchardat (Apollinaire),
_Quinologie_, Paris, 1854, 4°. 48 pages, and 23
good coloured plates exhibiting all the barks then met
with in commerce.
Delondre (Augustin), see Soubeiran.
Gorkom (K. W. van), _Die Chinacultur auf Java_,
Leipzig, 1869, 61 pages. An account of the management of
the Dutch plantation.
Hesse (Oswald). This chemist has summarized his elaborate
researches on Cinchona in the German Dictionary of
Chemistry, articles Chinin, Cinchonin, etc. 1876-1877.
Howard (John Eliot), _Illustrations of the Nueva
Quinologia of Pavon_. London, 1862, folio, 163 pages
and 30 beautiful coloured plates.—Figures of Cinchona
mostly taken from Pavon’s specimens in the herbarium of
Madrid, and three plates representing the structure of
several barks.
Howard (J. E.), _Quinology of the East India
Plantations_. London, 1869, folio x. and 43
pages, with 3 coloured plates exhibiting structural
peculiarities of the barks of cultivated _Cinchonæ_.
Howard (J. E.) The same, parts ii. and iii., Lond. 1876,
folio xiv. and 74 p., with 2 views, 2 black plates
and 13 coloured figures of _Cinchona Calisaya_
(_Ledgeriana_), _C. officinalis_, _C.
pitayensis_, and others.
Karsten (Hermann), _Die medicinischen Chinarinden
Neu-Granada’s_. Berlin, 1858, 8°. 71 pages, and 2
plates showing microscopic structure of a few barks. An
English translation prepared under the supervision of
Mr. Markham, has been printed by the India Office under
the title of _Notes on the Medicinal Cinchona Barks of
New Granada by H. Karsten_, 1861. The plates have not
been reproduced.
Karsten (Hermann), _Floræ Columbiæ terrarumque adjacentium
specimina selecta_. Berolini, 1858, folio. Beautiful
coloured figures of various plants including Cinchona,
under which name are several species usually referred to
other genera. Only three parts have been published.
King (George), _A Manual of Cinchona cultivation in
India_. Calcutta, 1876, 80 pages, small folio.
Kuntze (Otto), _Cinchona. Arten, Hybriden and Cultur der
Chininbäume._ Leipzig, 1878. 124 pages and 3 plates.
A review of this book will be found in the _Archiv der
Pharmacie, 213_, (1878) 473-480.
McIvor (W. G.) _Notes on the propagation and cultivation
of the medicinal Cinchonas or Peruvian bark trees._
Madras, 1867, 33 pages, 9 plates. The author explains
the “motsing system” alluded to p. 362.
McIvor (William Graham), _A letter on the cultivation of
Chinchona on the Nilgiris_. Ootacamund, 1876, 27
pages.
Markham (Clements Robert), _The Chinchona Species of
New Granada, containing the botanical descriptions of
the species examined by Drs. Mutis and Karsten; with
some account of those botanists, and of the results
of their labours_. London, 1867, 8°. 139 pages and
5 plates. The plates are not coloured, yet are good
reduced copies of those contained in Karsten’s _Floræ
Columbiæ_; they represent the following:—_Cinchona
corymbosa_, _C. Trianæ_, _C. lancifolia_,
_C. cordifolia_, _C. tucujensis_.
Markham. _A Memoir of the Lady Ana de Osorio, Countess
of Chinchon, vice-queen of Peru_ (A.D.
1629-1639), _with a plea for the correct spelling of
the Chinchona genus_. London, 1874, 4°. 99 pages,
with a map, heraldic figures and views.
See also Hanbury, _Science Papers_, 1876, p. 475.
Miquel (Friedrich Anton Wilhelm), _De Cinchonæ speciebus
quibusdam, adjectis iis quæ in Java coluntur.
Commentatio ex Annalibus Musei Botanici Lugduno-Batavi
exscripta._ Amstelodami, 1869,4°. 20 pages.
Oudemans (Anthony Cornelis), _Sur le pouvoir rotatoire
spécifique des principaux alcaloïdes du quinquina_.
_Archives néerlandaises_, x. (1875), 193-268, and
xii. (1877).
Phoebus (Philipp), _Die Delondre-Bouchardat’schen
China-Rinden_. Giessien, 1864, 8°. 75 pages and a
table. The author gives a description without figures,
of the microscopic structure of the type-specimens
figured in Delondre and Bouchardat’s _Quinologie_.
Planchon (Gustave), _Des Quinquinas_. Paris et
Montpellier, 1864, 8°. 150 pages. A description of the
cinchonas and their barks. An English translation has
been issued under the superintendence of Mr. Markham by
the India Office, under the title of _Peruvian Barks
by Gustave Planchon_. London, printed by Eyre and
Spottiswoode, 1866.
Soubeiran (J. Léon) et Delondre (Augustin), _De
l’introduction et de l’acclimation des Cinchonas
dans les Indes néerlandaises et dans les Indes
britanniques_. Paris, 1868, 8°. 165 pages.
Triana (Josè), _Nouvelles études sur les Quinquinas_.
Paris, 1870, folio, 80 pages, and 33 plates. An
interesting account of the labours of Mutis, illustrated
by uncoloured copies of some of the drawings prepared
by him in illustration of his unpublished _Quinologia
de Bogotá_, especially of the several varieties
of _Cinchona lancifolia_; also an enumeration
and short descriptions of all the species of
_Cinchona_, and of New Granadian plants (chiefly
_Cascarilla_) formerly placed in that genus.
An abstract of the book will be found in Just’s
_Botanischer Jahresbericht_ für 1873, 484-494.
Vogl (August), _Chinarinden des Wiener Grosshandels und
der Wiener Sammlungen_. Wien, 1867, 8°. 134 pages,
no figures. A very exhaustive description of the
microscopic structure of the barks occurring in the
Vienna market, or preserved in the museums of that city.
Vogl (A.), _Beiträge zur Kenntniss der sogenannten
falschen Chinarinden_. Wien, 1876, 4°. 26 pages, 7
microscopic sections.
Vrij (John Eliza de), _Kinologische studiën_. More
than 30 papers published since 1868 in the _Nieuw
Tijdschrift voor de Pharmacie in Nederland_. They are
chiefly devoted to the chemistry of the barks from Java
and British India.
Weddell (Hugh Algernon), _Histoire naturelle des
Quinquinas, ou monographie du genre Cinchona, suivie
d’une description du genre Cascarilla et de quelques
autres plantes de la même tribu_. Paris, 1849, folio,
108 pages, 33 plates, and map. Excellent uncoloured
figures of Cinchona and some allied genera, and
beautiful coloured drawings of the officinal barks.
Plate I. exhibits the anatomical structure of the plant;
Plate II. that of the bark.
Weddell (H. A.), _Notes sur les Quinquinas, Extrait des
Annales des Sciences naturelles_, 5ᵉ série, tomes
xi. et xii. Paris, 1870, 8°. 75 pages. A systematic
arrangement of the genus _Cinchona_, and
description of its (33) species, accompanied by useful
remarks on their barks. An English translation has been
printed by the India Office with the title—_Notes
on the Quinquinas by H. A. Weddell_, London, 1871,
8°. 64 pages. A German edition by Dr. F. A Flückiger
has also appeared under the title _Uebersicht der
Cinchonen von H. A. Weddell_. Schaffhausen and
Berlin, 1871, 8°. 43 pages, with additions and indexes.