INTRODUCTORY ESSAY. . 3 



subjects worthy of future attention. Geographical distribu- 

 tion, and the effect of climate, soil, and exposure, have been 

 made the objects of our special study, and will in all cases be 

 particularly noted. With regard to economic botany, it is 



impossible to do more than briefly enumerate 

 ective species, the various products which ha\ 



must 



our readers to the many 



botanists 



facilitate 



mists 



tion of the plants which yield the products they seek. We 



medical 



nomic botany, and we announce boldly our 



tments 



still 



nntry. Hundreds 



while of most 



known only to the professed botanist. The mass must indeed 

 always remain so : just as the refinements of the laboratory 

 and the calculations of the mathematician must ever be mys- 



majority of manufacturers 



are 



mis 



take to suppose that it can be otherwise ; or that those who 



use 



as philosophical botany, can command the time to become so 

 familiar with the details of the commercial value of vegetable 

 products, as to be safe referees on these subjects. On the 



qually 



economic products, can 

 knowledge necessary to 

 plants trustworthy 



the eves of men of science*. It is therefore as a strictly 



ave only to refer to the pages of any book on me- 

 and to the fact, first indicated in these pages, that 

 about which so much has been written, if produced 



