xiv PREFACE. 



and left of it in small Eoman letters the names of those Orders 

 which are supposed to be in nearest alliance to it ; and above and 

 below it in italic type the names of such as are only analogous^ 

 or at least have a more distant affinity. The idea of this is 

 borrowed from Mr. Strickland^ s excellent paper on the true method 

 of discovering the Natural System in Zoology and Botany^ printed 

 in the Annals of Natural History, vol. vi. p. 184. 



The uses to which plants are applied has been re-examined with 

 great care, and principally re-wi'itten. This part was originally 

 intended as a mere sketch of so vast and important a subject, and 

 in truth it is little more even now. It is, however, materially en- 

 larged, and the Author hopes better arranged. In preparing it great 

 numbers of works have been consulted, and most especially the 

 special treatises of Dierbach, Fee, Geiger, Guibourt, Martins, 

 Nees V. Esenbeck, Perena, Richard, and Royle, together with the 

 capital condensation published by Endlicher in his Enchiridion. 

 The Author was also strongly ad\dsed by one whose opinion has 

 great weight with him, to introduce among the properties of plants 

 an account of their proximate principles and ultimate constituents. 

 But after a full consideration of the subject, he has come to the 

 conclusion that it is not expedient to do so. In the first place, 

 such matters belong to Chemistry, and not to Botany ; secondly, 

 it does not appear possible to connect them with any known prin- 

 ciple of botanical classification; and, moreover, the extremely 

 unsteady condition of the opinions of chemists themselves upon 

 the result of their own researches, and the uncertainty at present 

 connected with the details of organic chemistry, would render the 

 introduction of the supposed results of chemists embarrassing 

 rather than advantageous. If it is true, as appears to be admitted, 

 that such principles as Caff'eine and Theine are identical, and that 

 oils of Anise and Tarragon are chemically undistinguishable, it is 

 clear that these substances can have no connexion with structm-e, 

 or Botanical classification, if indeed they are not altogether arti- 

 ficial products produced by chemical processes, like Dr. Fownes^s 

 furfurol — a vegeto-alkaH resulting from the distillation of bran, 

 sulphuric acid, and water. 



In forming the lists of genera, the Author is called upon to 

 acknowledge the great assistance that he has derived from those 

 of Professor Endhcher, which indeed he has ventm-ed to take as 

 the foundation of his own, making however considerable additions 

 and material changes in some, and entirely re-writing others ; 



