214 THE POPULAR SCIENCE MONTHLY. 



I mention this not as an isolated example of what is being ac- 

 complished in commercial botany, but as a fair illustration of the 

 thoroughness with which the problems are being attacked. It 

 should be further stated that at the garden in question assiduous 

 students of the subject are eagerly welcomed and are provided 

 with all needed appliances for carrying on technical, chemical, and 

 pharmaceutical investigations. Therefore I am justified in saying 

 that there is every reason for believing that in the very near fu- 

 ture new sources of our most important products will be opened 

 up, and new areas placed under successful cultivation. 



At this point attention must be called to a very modest and 

 convenient hand-book on the Commercial Botany of the Nineteenth 

 Century, by Mr. Jackson, of the Botanical Museum attached to the 

 Royal Gardens, Eew, which not only embodies a great amount of 

 well-arranged information relative to the new useful plants, but 

 is, at the same time, a record of the existing state of things in all 

 these departments of activity. 



VIII. Fragrant Plants.— Another illustration of our subject 

 might be drawn from a class of plants which repays close study 

 from a biological point of view, namely, those which yield per- 

 fumes. 



In speaking of the future of our fragrant plants we must dis- 

 tinguish between those of commercial value and those of purely 

 horticultural interest. The former will be less and less cultivated 

 in proportion as synthetic chemistry by its manufacture of per- 

 fumes replaces the natural by the artificial products, for example, 

 coumarin, vanillin, nerolin, heliotropin, and even oil of winter- 

 green. 



But do not understand me as intimating that chemistry can 

 ever furnish substitutes for living fragrant plants. Our gardens 

 will always be sweetened by them, and the possibilities in this 

 direction will continue to extend both by contributions from 

 abroad and by improvement in our present cultivated varieties. 

 Among the foreign acquisitions are the fragrant species of Andro- 

 pogon. Who would suspect that the tropical relatives of our sand- 

 loving grasses are of high commercial value as sources of per- 

 fumery oils ? 



The utility to the plant of fragrance in the flower, and the 

 relation of this to cross-fertilization, are apparent to even a casual 

 observer. But the fragrance of an aromatic leaf does not always 

 give us the reason for its being. 



It has been suggested for certain cases that the volatile oils 

 escaping from the plants in question may, by absorption, exert a 

 direct influence in mitigating the fierceness of action of the sun's 

 rays. Other explanations have also been made, some of which are 

 even more fanciful than the last. 



