xxiv 



INTRODUCTION. 



great inventor himself confessed his scheme to 

 be imperfect, and recommended it only as a 

 substitute for some undiscovered system, which 

 should associate plants of similar structm^e ; his 

 own method being open to the objection that it 

 brought together those which were not physiolo- 

 gically connected, and separated many which 

 were closely related. Modern botanists have 

 freely availed themselves of the discoveries of 

 Linn^us, and have undoubtedly made consider- 

 able advances tovrards a Natural System, against 

 which this objection cannot be urged, but they 

 have neglected to tender their acknowledgments 

 to one who did more to dissipate the gloom in 

 which the science of Xatural History was shroud- 

 ed, than any, or even all, of his predecessors. 



It has been already stated, that all our British 

 trees are in their growth exogenous : hence they 

 are arranged in a class, together with nmnberless 

 herbs, shrubs, and trees, and called Exogens, 

 They are distinguished by the marks given above, 

 and by their seeds being composed of at least 

 two lobes, called cotyledons, held together by a 

 minute organ, the upper part of which, the 

 plumule (a little feather), is a rudimentary stem ; 



the lower, the radicle, is, as its 

 name implies, a rudimentary root. 

 The cotyledons are leaves, dif- 

 fering in shape from those after- 

 wards developed, and serving to 

 nourish the young plant until 

 COTYLEDONS OF proper leaves are formed. When 

 ^^'^^* the seeds germinate, the coty- 

 ledons generally rise above the ground, bringing 

 the plumule with them : sometimes, as in the 



