The production of commercial barks is limited to about a dozen species. Of these, three only are admitted for pharmaceutical use, the remainder being employed only in the manufacture of the alkaloids. Tho former arc :— (1) C. officinalis, of several varieties; native of Ecuador and Peru, forming a large tree ; yields " Pale," " Loxa," or " Crown " bark, found in quills sometimes 1 ft. long, = in. thick. (2) C. Calisaya, of many varieties ; native of the warmest woods of the slopes bordering the valleys in the Bolivian provinces of Enquisivi, Yungas de la Pax, Larecaja (Sonata), Canpolican (Apolobamba), and Munccas, and the Peruvian province of Carabaya, at elevations of 5900-6000 ft. ; attains great height and size ; affords " Calisaya," " Bolivian," or " Yellow " bark, the most important of those commonly used, found (a) in flat pieces, 1 ft. or more long, 1-4 in. wide, and in. thick (= " flat "), and (b) in tubes 1-1} in. thick (= "quill "). (3) C. succi rubra, native of all the Andean valleys debauching on the plain of Guayaquil, but now almost con fined to the woods of Guaranda, on the W. slopes of Chimborazo, at 2000-5000 ft. ; forms a tree of 50-80 ft.; yields the " Red " bark, so named from its distinctive colour ; is held in least esteem in England, but when of deep brilliant tint is readily sold at a high figure for the Parisian markets. The members of the second class are principally :—(1) C. macrocalyx, of Peru, affording " Ashy Crown " bark ; its sub-species C. Patton yields " Palton " bark, much used for making quinine. (2) C. lanceolata, of Peru, yields " Carthagena" bark, confounded with " Palton," but not so good. (3) C. lancifolia, of New Granada, affords " Columbian " bark, very largely used for quinine; a variety gives "Soft Columbian" bark. (4) C. pitayensis, of New Granada, furnishes "Pitayo " bark, very valuable for the preparation of alkaloids, being the chief source of quinidine. (5) C. australis, of S. Bolivia, produces a poor bark, often mixed with Calisaya. (6, 7, 8) C. Peru viana, C. nitida, and C. micrantha, all of Peru, contribute " Grey," " Huanuco," or " Lima " bark, chiefly employed on the Continent. (9) C. cordifolia, of New Granada and Peru ; some of its varieties furnish a portion of the " Columbian " bark, and are used for the preparation of alkaloids. A new variety, called China cuprea, has recently appeared in the London market. Its inner surface is very smooth. It contains about 2 per cent. of quinine, and but little resinous matter.
The collection of the bark in S. American forests is an arduous occupation, followed only by the Indians and half-breeds. The stem of the tree is first freed from parasitic growth, and is then beaten, to remove the sapless outer bark. Vertical and cross cuts are next made in the inner bark, as high as can be reached; the tree is felled, and the inner bark is completely stripped off. The latter is then dried, by sun-heat where possible; failing that, the hark is spread on hurdles over a camp-fire. The thinner pieces roll up into "quills," while the thicker portions are kept flat by weights. The bark of the roots is sometimes added. When dry, the barks are sorted according to size, sometimes pressed, and packed in parcels of 100 lb. and upwards, in serons of raw bullock hide, or in wooden chests. In this state, the drug is carried to the coast for shipment to Europe.
The destructive and wasteful manner of collecting the bark, pursued by the inhabitants of the natural home of the tree, has led to its extermination in many places, and it is now confined within very narrow limits. The value of the drug in tropical medicine has compelled us to attempt its
cultivation in most of our Colonies, and more especially in India, in order that we might not be dependent upon countries which produced it in insufficient quantity, yet monopolized the supply. The introduction of the trees into India was successfully accomplished, in spite of extraordinary difficulties, by the rare intelligence and energy of C. R. Markham, C.B., F.R.S., and those who assisted him. The cultivation of cinchona is now a recognized branch of the planting industry of India, Ceylon, W.Indies, &c., and is largely carried on by the Dutch in Java. The following account of the culture and barking of the trees, and the preparation of the alkaloids, has reference specially to India ; it will be supplemented by a brief notice of the condition of the enterprise in other countries.
Cuurivenow.—Neglecting, for the moment, to specify the localities where cinchona cultivation promises to be a success, it will, perhaps, be better first to indicate the necessary natural conditions, and the methods which have been adopted after years of experience.
Climate.—None of the medicinal cinchonas survive frost ; they prefer a moderate and constantly equable warmth, the moat congenial temperature for yellow and red barks iu company being about as follows :—Max., 34° (92°-4° F.) ; min., 4°-5° (40°-1° F.); mean max., 27° (80 6°-81 .6° F.); mean min., 15°-16° F.); mean, 21°-22°70°-7l'26° F.) Excessive moisture is preju dicial, and a sudden burst of sunshine after protracted wet also does harm, while all species can withstand drought ; a constant alternation of showers and sunshine is most favourable. The annual rainfall may be about 100-150 in., and should be uniformly distributed, and gentle in character. Hail does not commit permanent damage ; but storms of wind are very injurious, especially to yellow barks. Elevation will of course vary with latitude and other conditions. In the Nilgiris, yellow barks succeed best at 4500-6000 ft.; crown barks, up to 8500 ft.; red and grey barks, best within the yellow zone, but nowhere well. In Sikkim, yellow and grey barks thrive at 800-5000 ft., best at 1500-3500 ft.; red, at 1500-3000 ft.; crown, not at all.
Soil and Drainage.—The trees prefer a rich soil, and thrive better on newly cleared forest-land than on grass-land ; but the crown barks do fairly well in poor ground. While a free and friable surface-soil is beneficial, an open subsoil is absolutely necessary. The least stagnation of water at the roots is fatal to all species ; perfect drainage must, therefore, be secured by a sloping situa tion, and other conditions.
Collecting Seeds.—The seeds mostly ripen during the dry season following the rains, and should be carefully gathered just as the vessels begin bursting. The latter are then spread in shallow boxes, to dry until the seeds fall out, the desiccation being best accomplished by placing them in a draught during the day, covering them from rain, and from dew at night. They soon lose vitality, and should be sown at once ; they are best transported in porous cloth, ventilation being essential. About 20,000-25,000 plants are produced by 1 oz. of clean seed.