ORCHIDACEJE 



as systematists are not in absolute agreement. While a concur- 

 rence of opinion maybe found in regard to several particular gen- 

 era, a variance of opinion will exist as to others. Each systematist 

 is hkely to attribute to some character a value which his associates 

 fail to recognize. Abstractly there seems to be general agreement 

 among botanists as to the value of classificatory groups, although 

 they differ so considerably in the application of their rules. In 

 his discussion of the classifications used by botanists and zoo- 

 logists Herbert Spencer has said that "when aggregating the 

 smallest groups into larger groups and these into groups still 

 larger, they have adopted certain general terms expressive of the 

 successively more comprehensive divisions ; and the habitual use 

 of these terms, needful for purposes of convenience, has lead to 

 the tacit assumption that they answer to actuaUties in Nature. 

 It has been taken for granted that species, genera, orders, and 

 classes, are assemblages of definite values — that every genus is 

 the equivalent of every other genus in respect of its degree of 

 distinctness ; and that orders are separated by lines of demarca- 

 tion which are as broad in one place as another. Though this 

 conviction is not a formulated one, the disputes continually oc- 

 curring among naturahsts on the questions, whether such and 

 such organisms are specifically or generically distinct, and whether 

 this or that peculiarity is or is not of ordinal importance, imply 

 that the conviction is entertained even where not avowed."^ Fur- 

 thermore, the same author says that "it is a wholly gratuitous 

 assumption that organisms admit of being placed in groups of 

 equivalent values." And according to the present status of sys- 

 tematic botany this is undoubtedly true, and necessarily so, as 

 the same viewpoint can scarcely be held in regard to all classes 

 of organisms, and as characters which in one family or tribe 



1 The Principles of Biology. 



[4] 



