PREFACE. 



to begone of them), should be as free as possible; so 



that the " pith and marrow," which the student is 



-'i 



required to be acquainted with, should be attainable 

 at once. That the dogmatic and half-sententious man- 

 ner induced in the author, and imbibed by the reader, 

 where this principle is acted upon, may lead to bad 

 consequences, is no doubt true ; and that the one may 

 think he has performed all that he ought to have done, 

 and that rightly, and the other that he has learned all he 

 ought to have learned, and that soundly, whilst both may 

 be egregiously mistaken, may be equally certain ; but 

 whilst there may be some who consider that there 

 are existing necessities requiring the risking of such 

 consequences as these and others attendant upon them, 

 and that they may perhaps be balanced by other results, 

 they will be tempted, probably like the author, to ad- 

 minister to such necessary requisitions. 



It occurred to the author during the completion of 

 the work, that he ought perhaps to have noticed several 

 points he has left untouched, such as the elements of 

 Phyto-geography and Phyto-geology, tbo chemical com- 

 position and relationships of elementary structures, etc., 

 and to have given a short introduction illustrative of 



