Q TUE I'rriSIOUNOMY AND PHYSIOLOGY 



above ninety thousand species of plants ; while 

 vast districts of our globe remain unexplored, 

 and the productions of others are but little 

 known ; so that it has been calculated by those 

 best able to form an opinion, that at least two 

 hundred thousand species of plants tenant the 

 earth. To how few of these, in the present 

 state of our knowledge, can any practical use be 

 assigned ! and yet we know that God has madf- 

 nothing in vain, and every year's discoveries 

 reveal some fresh proof of this. Plants, which 

 have appeared useless before, are found to play 

 important parts in the economy of the natural 

 world ; or properties, hitherto iraknown, are 

 detected in them, which render them valuable. 

 Let the applications of the recently discovered 

 gutta percha — the continual additions made 

 from the vegetable kingdom to the resources of 

 the healing art — and the discovery of the nume- 

 rous useful products of bog-peat by Mr. liccce, 

 serve as examples. 



Although, to an ordinary observer, the vast 

 number of species of plants might seem to pre- 

 sent such a variety of appearance and character, 

 as to render any attempt to classify them a 

 hopeless task, yet it Avill be readily observed, 

 that some large sections cf the whole stand out 

 with so marked and striking a family likeness, 



