PRINCIPLES OF CLASSIFICATION 137 



according to characters arbitrarily chosen. 

 Then any one wishing to identify an unknown 

 variety could follow out the arbitrary key or 

 classification, while any one wishing to study 

 the varieties broadly would have recourse to 

 the natural classification. 



It should be remarked, for the benefit of 

 those who are accustomed to the use of the 

 current manuals of botany, such as Gray's 

 Manual, that these books employ, more or 

 less successfully, the double method outlined. 

 The keys given in these books for help 

 in tracing out (" analyzing," as they say in 

 school) plants whose names are not known 

 are purely artificial. The arrangement of 

 plants into species, genera, and families, ac- 

 cording to their broad resemblances, is natu- 

 ral at least, it is professedly so ; and though 

 the books frequently fall far short of the 

 whole truth in these qualifications, yet the 

 arrangements are on a natural basis. 



All these matters will appear more clearly 

 when we take up some of the actual examples 

 of classification, as we shall now proceed to 

 do. The author feels that some explanation 

 is fairly due the student for the introduction 

 of the following very imperfect, and often 



