PREFACE. XI 



however, only to mark the greater parts, their 

 limits, and their connections, leaving the minor 

 and less striking portions of vegetable structure 

 to those who may have better opportunities to 

 examine and describe them. 



On this plan the work will be found a com- 

 pendium of the discoveries and best authenticated 

 facts which have appeared in the writings of 

 others, and which have been proved in the prac- 

 tice and experience of the writer, or in that of 

 his cotemporaries, during the last fifty years. 

 He trusts that new matter enough will be found 

 to justify the publication; and though but a 

 rough sketch, which from his very limited know- 

 ledge of chemistry he has not been able to fill up 

 as he wished, still he entertains a hope that, such 

 as it is, it may receive amplification from an 

 abler pen, and accomplish his aim of rendering 

 vegetable physiology better and more generally 

 understood. 



As many of the ideas in the first essays are 

 detailed without proofs, the latter will be found 



