viii PREFACE. 



ment, or the great experience which a long and most 

 successful career of public instruction has necessarily 

 given him. 



I have begun with what is called ORGANOGRAPHY 

 (Book I.) ; or an explanation of the exact structure of 

 plants ; a branch of the subject comprehending what 

 relates either to the various forms of tissue of which 

 vegetables are constructed, or to the external appear- 

 ance their elementary organs assume in a state of com- 

 bination. It is exceedingly desirable that these topics 

 should be well understood, because they form the basis 

 of all other parts of the science. In physiology, every 

 function is executed through the agency of the organs : 

 ^systematic arrangements depend upon characters arising 

 out of physiological considerations ; and descriptive 

 Botany can have no logical precision until the prin- 

 ciples of Organography are exactly settled. A dif- 

 ference of opinion exists among the most distinguished 

 botanists, upon some points connected with this subject, 

 so that it has been found expedient to enter occasionally 

 into much detail, for the purpose of satisfying the stu- 

 dent of the accuracy of the facts and reasonings upon 

 which he is expected to rely. 



To this succeeds VEGETABLE PHYSIOLOGY (Book II.) ; 

 or the History of the vital phenomena that have been 

 observed both in plants in general, and in particular 

 species, and also in each of their organs taken separately. 

 It is that part of the science which has the most direct 

 bearing upon practical objects. Its laws, however, are 

 either unintelligible, or susceptible of no exact apprecia- 

 tion, without a previous acquaintance with the more im- 

 portant details of Organography. Much of the subject 



