botanists, set out for South America. They were scarcely more fortunate, as regards their collections, than De Jussieu had been. Once their specimens were destroyed by shipwreck on the coast of Portugal, while a second accumulation was destroyed by fire in 1785. After the return of Ruiz and Pavon to Spain, their pupil Tafalla continued to investigate the Peruvian cinchonas. The results at which he arrived are given in the 'Flora Peruviana,' 1798–1802; in the 'Quinologia' of Ruiz, published at Madrid in 1792; and in a supplement to the latter work, issued in 1801.

The Bolivian barks were first studied by Haenke, a German traveller, who in 1785 traversed a district subsequently visited by Dr. Weddell.

Poeppig, Professor of Botany at Leipsig, travelled in Peru and Chili during the years 1827-1832, and added much to our knowledge of the grey barks of Huanuco.

Dr. Weddell, an eminent French botanist, paid two visits to Bolivia at the instance of the Government of Louis Philippe. An account of his travels is given in his 'Voyage dans le Nord de Bolivie,' Paris, 1853. His splendid monograph on the genus Cinchona, entitled 'Histoire Naturelle des Quinquinas,' Paris, 1849, was until recently the most valuable work of reference on the subject on which it treats. The information it contains respecting the Bolivian barks, and the mode of collecting them, together with the numerous beautiful illustrations of the various species of the genus, will always render this work a storehouse for those desiring a knowledge of this important genus. To this author we owe the first accurate description of the Cinchona Calisaya, one, if not the most valuable of the species.

Dr. Karsten's researches were conducted principally in New Granada, and an account of them is given in a splendidly illustrated work, called Flors Columbia Specimina Selecta,' Berlin, 1858; and also in a pamphlet published in 1858, and translated into English at the instance of Mr. Markham. It is to be regretted that the translation of this pamphlet, whose title is given at the head of the present notice, was not more carefully performed.

The distinguished quinologist, Mr. Howard, after having, at the suggestion of Dr. Pereira, availed himself of Pavon's specimens of barks in the British Museum, and of other sources of information open to him in this country,* caused inquiries to be made in Spain, and in 1858 was enabled to purchase fifty-four of Pavon's specimens of barks, with an unpublished manuscript, descriptive of several species of cinchona discovered by Pavon and others. Subsequently, having learnt that the original specimens described in the manuscript were still in existence at the Royal Museum of Madrid, Mr. Howard commissioned the well-known botanical artist, Fitch, to go to Madrid and make drawings from these specimens. These drawings, together with some supplied by Mr. Howard, and three showing the microscopical structure of the barks, with other botanical details from the pencil of Mr. Tuffen West, constitute the magnificent volume with which Mr.

* Examination of Pavon's Collection of Peruvian Barks contained in the British Museum. London, 1853, and Appendix 1855. Pharmaceutical Journal, 1854, 1856.

Howard has enriched pharmacological and botanical science. There may be differences of opinion as to the specific value of some of the forms described by Mr. Howard, and as to the importance of the characters he relies upon for their discrimination; but there can be but one feeling of admiration for the superbly illustrated work, which from genuine love of science, and at great cost to himself, he has placed before the public. A reference to Pereira, Royle, and others of our text-books, will give the reader further details as to the works published on the subject of cinchona, and of which Bergen, who wrote as far back as 1826, enumerates no less than 637! The information therein contained has become more or less obsolete, owing to the more accurate information contained in the works of Weddell, Howard, Karsten, and others, laid under contribution in the compilation of the present notice. Thus much, in brief, for the history of the plants.

We can do no more than allude to the disputes which arose soon after the introduction of the drug into Europe as to its efficacy, as it may now safely be assumed that the balance of evidence is decidedly in favour of the utility of these barks, and of the principles derived from them; although it must be confessed that no mean array of evidence might be cited to show that they are valueless. In the last century the debates on the subject ran fast and furious, and were not seldom tinctured by polemical acrimony and Protestant antipathy to the Jesuits. More recently, we find Majendie asserting, as the result of experimental observation, the inertness of the drug. These discrepancies arose partly from the confusion of the several kinds of bark trees by the botanists-a confusion accidental in some cases, but in others brought about by the jealousies of rival botanists. Commercial greed also operated in concealing the places where the trees grew, and the ports whence the bark was exported. In the course of this notice we hope to be able to show how other discrepancies may have arisen, and how likely they are again to be encountered, if the sources of fallacy be not sedulously hunted out and prevented.

The species of Cinchona are very unequally distributed in the forests on the eastern side of the Andes, from the extreme north of South America, in latitude 11° N., where they occur on the mountains of Santa Martha, to the forests of Bolivia, as far S. as 19° S. Speaking generally, the trees grow at an elevation of from 4000 to 8000 feet above the level of the sea.

The geological formations on which they are found are mica slate, gneiss, clay slates, and lower silurian rocks, covered, however, in most cases, by several inches of rich vegetable soil. The climate of the districts inhabited by the cinchonas is by no means an agreeable one, as witnessed by Dr. Karsten, who describes the rainy season as lasting for nine months in the year, during which time

"A steady rain is only interrupted during the day by short gleams of sunshine interchanging with clouds and mist, whilst in that part of the year which answers to our winter, cold nights in which the temperature of the air descends to freezing-point, are followed by days in which the rays of the sun, piercing here and there through the thick clouds, raise the temperature to 77° F., whilst the leaves are kept almost constantly bedewed by the continual mists."

The temperature of this vast region, as stated by Mr. Markham, ranges (to speak generally) from 60° to 80° F., thus corresponding pretty closely with the isotherms laid down by Dove for these regions. It is in the highest degree necessary to pay attention to these external conditions, for, to say the least, they are of equal importance with the selection of the proper species for medicinal uses. The medicinal properties of many plants vary extremely in the same species under dif ferent conditions, and even when no appreciable difference in those conditions can be traced. Identity in medicinal properties by no means corresponds with identity in structural characteristics in all cases, though it does so in many. Digitalis grown in the Himalayas is said to be nearly if not quite inert. On the other hand, hemp grown in this country is almost entirely devoid of the peculiar resinous principles so abundantly found in the same species growing in the hot sunny plains of India. But we need not go so far in search of instances of this kind. Enanthe crocata and Cicuta virosa, tolerably common plants in the south of England, where they have a well-established evil repute as poisonous plants, are both harmless on the other side of the Tweed, according to Dr. Christison. We have also the testimony of Dr. Karsten upon this point, with regard to the variability in medicinal virtues of Cinchona lancifolia in New Granada, and that of Mr. Spruce in the case of C. Condaminea, the qualities of whose bark vary accordingly as the tree has grown on the sides of the mountains most exposed to the rays of the evening or morning sun. Vegetable physiology is not at present competent to account for such peculiarities in a satisfactory manner, but it is at least necessary to bear them in mind in the experiments now being carried on, as the kind of cinchona-tree that is proved to yield quinine and valuable alkaloïds in Peru may by no means necessarily yield the same products when grown in other climes.

Although physiology affords us but little help in these questions, morphology and minute anatomy do give a little information of a valuable kind, but upon which too much stress must not be laid. Students confining themselves to the elaboration of one subject, are too apt to attach a greater degree of importance to appearances than that presented to the mind of a more widely experienced observer; and thus, although we are far from depreciating the observations of the quinologists and the relations they assert to exist between the minute structure of the barks and the proportion of valuable ingredients which they contain, we deem it to be essential that these observations should be contrasted with, and, as a meteorologist would say, corrected by, the general results obtained by vegetable anatomists in other plants. The anatomical structure of the cinchona barks does not differ in any important degree from that of exogenous trees in general. There is, on the exterior, an epidermis only seen on the younger twigs, as it is soon pushed off by the growth of the underlying corky layers (epiphlæum), which vary in thickness and colour in different species. Beneath this cellular corky layer is another series of cells, constituting the mesophlæum, or cellular envelope, whose constituent cells are of a different pattern from those of the outer corky

layers. This middle bark is the region in which the alkaloïds especially abound; in it, also, are many cells filled with a coloured resinous juice, and separating it from the liber or inner bark (endophlæum) are a few laticiferous ducts. The inner bark is distinguished by the presence, in greater or less numbers, of long wood cells" bast cells " traversing a matrix of cellular tissue, into which also the medullary or pith rays of the wood are prolonged. Within the liber is a layer of growing tissue, called the cambium, developing into bark on the outside, and into the true woody layers on the inner side. With these latter we have nothing to do at present. Although these bark layers are originally distinct, yet in process of time they become more or less confused, and the limits between them obliterated.

It is more especially the middle bark or cellular envelope that is valuable in a medicinal point of view, and in proportion to its thickness, as a general rule, is the value of the bark. It has long been known that the barks yielding most quinine have what is termed a short fibrous fracture, owing to the preponderance of cellular tissue over the woody tissue of the liber. It has also been remarked that those barks which are richest in quinine have their liber-cells most blocked up by woody deposits, although the alkaloïds exist chiefly in the other portions of the bark. Moreover, the early disappearance of a set of slender thin-walled vessels, called sap-vessels, is a characteristic of barks that are rich in organic bases. As a rule, subject to exception in the red bark, the best kinds of bark are the produce of trees grown in elevated situations, and in a comparatively cold atmosphere. In such localities the quantity of woody tissue is comparatively slight in proportion to the cellular tissue, in which the alkaloïds are stored up. Our limits do not permit us to enter at greater length into this part of our subject; the illustrations of Mr. Tuffen West in Mr. Howard's volume, and those in Weddell's Histoire Nat. des Quinquinas,' will be of more service to the inquirer than pages of description. We must not, however, omit to note a curious circumstance mentioned by Mr. Howard, viz., the formation of crystals in the bark, outside the cells. These crystals Mr. Howard shows, by chemical analysis, to be really crystalline alkaloïds, and not mere raphides, such as abound in the cells and juices of most plants. The crystals in question are supposed to be post-mortem depositions from the sap. The alkaloïds are supposed by Dr. de Vry, a Dutch chemist, associated with Junghuhn in the experimental cultivation of the cinchonas in Java, to be produced by a reaction between the ammonia contained in the bark and the cincho-tannic acid. Mr. Howard, moreover, has shown that the bark of the trunk contains the largest quantity of alkaloïds; hence the flat table pieces or large quills should be preferred to small quills, the produce of young branches, in which the astringent principles especially prevail. The rind of the root is also, to a great extent, destitute of alkaloïds; hence Mr. Howard points out the improvidence of stripping the roots, and thereby not only getting a useless product, but also endangering the life of the tree, and thus preventing the formation of suckers, by means of which the felled tree might ultimately be replaced.

Karsten and other observers have shown that certain more obvious structural peculiarities than any that have just been mentioned may be employed to distinguish the valuable from the inert kinds. "It may certainly be assumed," says Dr. Karsten, “that the Cinchona with the capsule opening from the base upward and crowned by the calyx, and having moreover a corolla of delicate texture, with bearded edges and generally unindented seed-lobes, give a bark which may be considered pharmaco-dynamically as anti-periodic," while other nearly allied species, but differing in the foregoing particulars, possess only astringent and tonic properties. Dr. Karsten even goes further than this, for he says that the proper average quantity of the organic bases in the bark of the different genuine Cinchona can be nearly estimated from their form. "The short oval or elliptic capsules crowned by the calyx, the perforated or not perforated seed-lobe border, as well as the little pits (scrobicules) which appear in the axillary vein, near the midrib of the comparatively small leather-like leaves, are signs of a regularly larger quantity of alkaloïd in the plant so characterized, while the largeleaved, unpitted kinds, as well as those with long lance-shaped capsules, or with porous or perforated seed-lobe borders, as in C. purpurea, &c., show a small quantity or a total absence of quinine and cinchonine." Unfortunately this theory, however applicable in many cases, and to those that fell under Dr. Karsten's own observation, is falsified in other cases, and notoriously so in the case of the most highly esteemed species, C. succirubra. That the relations between anatomical conformation and chemical constitution should be fully worked out, is most desirable, as many of the discrepancies before alluded to may be accounted for by the wrong kind of bark having been employed.

In spite of Mr. Howard's statement, that the difference in the structure of the true and false barks is evident to the naked eye, we think that the ordinary medical practitioner, with his scanty leisure and multifarious duties, will do well to leave the discrimination and selection of barks to the professed pharmacist.

Of the numerous species described by botanists as belonging to this genus, only a few have been proven to possess valuable properties, while others have been shown to be entirely inert. Before giving the list of valuable species, we feel constrained to say a word or two about the nomenclature, already sufficiently involved, and likely from inju dicious changes to become more so. First, as to the name of the genus Chincona, or Cinchona. Linnæus, erroneously no doubt, wrote the latter, which has been up to this time universally adopted by botanists, pharmacists, and medical men. Mr. Markham's suggestion to alter established usage is therefore objectionable: the change, however, is so slight, that we apprehend no practical inconvenience will arise, whichever way the name be spelt. As to the species, the case is different: these have been named and renamed, according to the views of particular authors, till confusion has become worse confounded. Fortunately for our present purpose, one only of the medicinal species to be hereafter mentioned suffers under this horrible malady, caused by conflicting synonyms. Let us explain: in the works of Weddell, Howard, and other recent writers, the species yielding the various kinds of