172 AGRICULTURAT. REPORT. 



Snlphate of quinine 1 . 7r» 



Sulphate of cincboniclinc 1.50 



Cinciioiiiuc 08 



Total 3.33 



It thus appears tliat in the third generation the plants had acquired 

 such an acclimatization that the quinine product was almost exactly 

 equal to that of the first generation grown in its native habitat, on the 

 mountains of Peru. Subsequent experiments in cultivation seem to 

 show that not only can the same amount of alkaloids be obtained from 

 trees of Indian gTowth, but that in some species, at least, a decided in- 

 crease can be procured, especially through the system of mossing the 

 bark. 



Mossing the harlc. — This is one of the most imiiortant discoveries 

 with regard to cinchona culture. Mr. Mclvor tells us that his idea of 

 artificially applying moss to the bark of our cinchona plants originated 

 from the fact that the best cinchona bark of commerce is invariably over- 

 grown with moss. Hence the supposition that moss preserved the 

 alkaloids from oxidation or deterioration, which they apparently undergo 

 when the bark is long exposed to the full action of light. Mr. Mclvor's 

 plan is thus described : In removing the strip of bark, two parallel cuts 

 should be made down the stem at the distance apart of the intended 

 width of the strip of bark; the bark is then raised from the sides of the 

 cut and drawn off, beginning from the bottom, care being taken not to 

 press or injure the sappy matter (cambium) left upon the trunk of the 

 tree. This cambium, or sappy matter, immediately granulates on the 

 removal of the bark, and, being covered, forms a nevv^ bark, which main- 

 tains the circulation undisturbed. In this way successive crops of bark 

 are obtained from the same trees, and thus is avoided that wholesale 

 destruction of trees which takes place in the native habitat of the cin- 

 chonas, by the practice of felling the trees to obtain the bark. 



Benetcal of tJie lai'lc. — It will be a matter of surprise to some that a 

 tree may be stripped of its bark on the main trunk without the entire 

 ruin of the tree. But it is known that this work may be performed 

 under certain circumstances with impunity. It must be performed when 

 the bark is readily separable on account of the descent of the juices, 

 of which the new cambium layer is made. And the denuded body of 

 the tree must be kept moist, shielded from exposure to the sun, and 

 from heavy rains, which would injure or destroy the vital changes to be 

 effected in the new deposit. With these precautions, it has been claimed 

 that even fruit-trees may be stripped of their bark with safety. 



Source of the renewed harlc. — This important physiological question is 

 discussed at length by Mr. Howard. Our ideas on this subject are gen- 

 erally formed from the results which usually follow when incisions with 

 an axe are made into the body of a tree. Here the wound is closed up 

 generally by the gradual extension of new material from the upper sur- 

 face of the cut. But in these cases there is usually more or less removal 

 of the wood with the bark, and the surface being left exposed to the 

 sunlight, is quickly dried up and rendered incapable of vital action. 

 Many years ago the attention of the French vegetable physiologists was 

 directed to this subject. In 1852, M. Trecul submitted to the Academy 

 of Sciences the trunk of a black-gum tree, (N'yssa^) brought from Loui- 

 siana, where it had been protected by the shatle of a damp, marshy 

 forest from the direct action of the sun. It had been deprived of its 

 bark for the space of sixteen or seventeen inches all around the stem, 

 and nevertheless not only continued to grow, but bore leaves and fruit. 



