342 



CULTIVATION OF MEDICINAL PLANTS. 



Rhodium 

 wood. 



1867. tageous to grow sugar, coffee, cotton and cacao than to collect 

 the forest-products which in earlier times formed articles of 

 trade. To this cause I think we must attribute the disap- 

 pearance from commerce of such drugs as South American 

 Elemi, Idquidambar Eesin, the fragrant Tacamahaca, Caranna, 

 Winter's Bark and Contrayerva Eoot, all of which were fur- 

 nished by the Spanish colonies a century ago. 



Turning to the Old World, we may note the disappearance of 

 the sweet-scented Ehodium wood once found in our shops. 

 This substance is derived from two remarkable shrubby species 

 of Convolvulus occurring in the Canaries, in which islands, 

 however, as I have been informed by Dr. Bolle, who at my 

 request made special inquiries on the subject, no shrubs are 

 now to be found having woody stems thick enough to be worth 

 collecting. The oil of Ehodium sold in the shops is well known 

 to be an artificial compound. 



Sagapenum. Sagapenum may also be mentioned as a drug that has almost 



ceased to be imported ; and it is one of which we know neither 



the botanical source nor exact place of production, a remark 



that applies to another gum-resin of the same class, namely, 



Opopanax. opopanax. 



From considerations such as the foregoing, it becomes evident 

 that the supply of many drugs which are obtained without 

 culture is of necessity fluctuating and precarious and most 

 persons will be disposed to acquiesce in the remark of an 

 accomplished modern traveller and naturalist, that " whatever 

 vegetable substance is needful to man, he must ultimately 

 cultivate the plant producing it." This indeed is a truth exem- 

 plified in many ways. In the animal kingdom we find it 

 needful to cultivate, so to speak, both oysters and salmon, while 

 partridges, pheasants, grouse, hares and foxes all receive in our 

 island protection sufficient to save them from extermination. 

 In the vegetable kingdom, and in that branch of it with which 

 we have to do, there are several medicinal plants once easily 

 procured in a wild state which it has now become necessary to 

 cultivate. Henbane, belladonna, foxglove, hemlock, penny- 

 royal and valerian have all to be cultivated, in order that 



Necessity for 

 cultivation. 



