Popular Science Monthly/Volume 21/May 1882/The Tree That Bears Quinine
|THE TREE THAT BEARS QUININE.|
THE introduction of cinchona-culture into India was commenced in 1862. The rapid destruction of the cinchona-tree in South America, owing to the reckless method of gathering the bark, and the consequent high price of quinine in a country where that drug holds so important a rank, led the Government of India to try the experiment of introducing the tree into the waste mountainous regions of that country. Difficulties almost insurmountable were at first presented in obtaining young plants and seeds from the cinchona regions of the Andes, on account of the obstacles thrown in the way by the different South American governments. Several years passed before a sufficient number of plants could be secured for purposes of experiment.
Experimental gardens were opened on the Nilgiri Mountains of Southern India, the Himalayas on the north of Bengal, the hills of Assam and the Northwest Provinces, and on the highlands of Burmah. With the exception of the Nilgiri and Himalayas, these localities were found to be unfavorable.
At Darjeeling in the Himalayas, four hundred miles north of Calcutta, near which the cinchona-gardens are located, I gathered the following particulars of the introduction and culture of the cinchona-tree, and the manufacture and use of its alkaloids:
1. The soil, climate, and temperature of the cinchona regions of the Andes were carefully noted. Gneiss and mica schist in a somewhat loose and decomposed state, with a covering of vegetable mold, at such an altitude as would secure a moist temperature with the least possible variability, were the observed conditions, and these were sought for in the Himalayas. Gneiss and mica schist compose the prevailing formation throughout the Himalayan range, except its snow-capped summits, which are granite. To find the proper altitude was a more difficult matter. The higher and lower were at first tried, but it was found that an elevation of from four to five thousand feet above the sea-level afforded the most favorable conditions.
The soil is, as far as possible, identical with that of the Andes. The eastern terminus of the Himalayan range, being nearest to the sea, and in the range of the southeast monsoon, which on land is southwest, is constantly shrouded in mist, so much so that the rays of the sun are seldom clear. The eternal snows and glaciers are here not more than fifty miles from the burning plains of Bengal, the highest peak, the second in the world, being more than twenty-eight thousand feet above sea-level. The rain-fall is more than double that of the plains, the last ten years showing an average of one hundred and thirteen inches per year. A remarkably uniform temperature is thus secured, the extremes being 34° and 90°, while the ordinary summer range is between 60° and 70°, and the winter between 45° and 55°.
Several varieties of the cinchona have been tried. Some have failed entirely, while the C. saccirubra and C. salisaya prove the most hardy. The former of these has proved by far the most productive, and is now much more generally cultivated.
2. The seeds ripen at the commencement of the dry season succeeding the rains, i.e., in October and November. After being gathered they are spread out, in shallow boxes to dry. It is estimated that an ounce of seeds may produce from twenty to twenty-five thousand plants. When thoroughly dried they are sown in beds, and when well started the young plants are transferred to nursery beds protected from sun and rain by light thatched roofs. When from eight months to a year old, or about twelve inches high, they are ready to be planted out, the thatch-covering having been removed for a fortnight or so to harden them. Propagation by cuttings is practiced to some extent, and succeeds well. The plants are about six feet apart, and an acre of ground may produce a thousand or more trees.
Where vegetation is so rapid and profuse as in India, constant weeding is necessary, and, until the trees are sufficiently large to shade the ground, one or two weedings a year are highly beneficial. The following may be considered as a fair representation of the rapidity of growth:
At first, a very successful method was introduced for securing the bark without injury to the tree. Commencing with trees about eight years old, a strip of bark an inch and a half wide was taken from the trunk, extending from the lower limbs to the roots. Leaving a strip of equal width, an inch and a half, another was taken, and so on quite round the tree, thus removing one half and leaving one half intact. The whole trunk was then covered with moss, carefully bound on, so as to exclude the light and air. In from ten to eighteen months the bark would be found to be completely renewed without detriment to the growth of the tree. The new bark thus formed was found to be thicker and richer in quinine than the natural growth. This process could be repeated at intervals of from a year to a year and a half for an indefinite period. This method is still followed in the Nilgiris, while in the Himalayas it has failed on account of the ants, which penetrate the moss and destroy the exposed wood. In the Himalayas two methods are now practiced. By the first the trees are felled and the bark carefully peeled from the trunk and branches. The stumps are allowed to remain, and from the sprouts that spring up two of the most thrifty are preserved for future trees, while the rest are cut away. This is called coppicing. By the second method the tree is uprooted, and the bark removed from the trunk, branches, and roots. The ground is then replanted with seedlings. Time must show which of these methods will prove the most profitable.
The bark, on being removed from the trees, is placed in open sheds near at hand to dry, that the first process of drying may be in the open air and in the shade. When dried as much as possible without artificial heat it is carried to the dry-house, a close brick building, where the process is completed with the aid of slow charcoal-fires. The drying is thus accomplished, at the lowest possible temperature, without detriment to its chemical qualities. After this it may be stored without danger of deterioration.
3. The medicinal alkaloids contained in the bark are quinine, cinchonidine, quinidine, and cinchonine. Quinine has long been regarded as by far the most important of these, being the great specific for malarious fevers. The price of bark in the market has consequently varied with the amount of quinine it was found to contain, with very little reference to the other alkaloids. Careful experiments have shown that all these alkaloids possess a very high medicinal value, but little if at all inferior to quinine.
Malarious fevers, prevailing so extensively throughout India, and especially among the lower classes, the high price of quinine has rendered it absolutely prohibitory to the masses. Consequently, the Government has turned its attention to the production of an article that should contain, as far as possible, all the febrifuge qualities of quinine, at a rate so moderate as to come within the reach of all. This benevolent object has been fairly reached in the production of what is known as amorphous quinine, or cinchona alkaloid, which sells at about fifty cents per ounce, while quinine is held at from three to five dollars per ounce. The products of the government cinchona-gardens are largely employed in the manufacture of this drug.
The method of preparation is extremely simple. The bark, roughly pulverized, is macerated in cold water acidulated with sulphuric acid, until its properties are quite exhausted. Its resulting liquor is precipitated by a caustic alkali potash. The precipitate is then dried, pulverized, and sealed in tin boxes of a pound each. The powder is of a dull whitish color, very light, almost insoluble in water, but dissolves readily in acidulated water. At the time of issuing the last report, one hundred and forty thousand ounces of this febrifuge were being produced from the Himalaya gardens.
4. At an early period extensive experiments were instituted to ascertain the relative curative value of the different alkaloids. One commission, consisting of sixteen prominent medical officers, reported as follows:
The experiment was then varied, in which the alkaloids were pitted against quinine. The number of fever-cases treated was 2,472, with 2,445 cures and 27 failures. The ratio of failure per 1,000 was as follows:
|Treated||by||quinine||ratio of failure||7·092|
These results, corroborated as they are by many subsequent experiments, in various parts of India, conclusively show that all the alkaloids of cinchona possess a nearly equal curative value, and hence the conclusion is that all combined possess a value very little if at all inferior to quinine. The doses are about the same. Cinchona alkaloid is now largely used throughout the country, with a proportionate reduction in the demand for quinine.