THE CLASSIFICATION OF PLANTS 2121 



cessful. Linnaeus himself admitted the force of this conception of affinity 

 in proposing the idea of a Natural System. He suggested a list of families, 

 based upon the intuitive feeling of relationship, but left them undefined, 

 because he did not consider that knowledge was at that time sufficient to 

 do this, or in other words, to dress the natural model in logical garments. 

 How far later workers have succeeded in the attempt may be seen by any- 

 one who compares the definitions of families used in various textbooks of 

 Systematic Botany. Of course, the so-called intuitive feeling of affinity 

 among members of a family is not actually a non-rational process, but 

 consists in the summation by the observer of a large number of qualitative 

 sense data, expressed by the term " facies", many of which are either 

 individually minute or so elusive as to escape verbal definition, but which 

 are cumulatively recognized by the observer as a sense-group for which 

 there is a very strong presumption of natural reality. This was, and is, a 

 process of discovery and it stands in complete contrast to the procedure 

 which starts from a logical definition, such as characterized the confessedly 

 artificial systems and which still finds its way, clandestinely, into later and 

 presumptively natural systems. What is true of the recognition of families 

 is true also of the recognition of genera and of species in their difi^ering 

 degrees. 



It is often assumed that if we proceed by discovery, we shall, in uncover- 

 ing natural relationships, uncover at the same time the evolutionary history 

 of the organisms, but this is based upon a misconception. It presupposes 

 that if species A has a character or characters which are believed (as, for 

 example, where evident signs of reduction are present) to be more advanced 

 than the corresponding characters in species B, then species A stands above 

 and is derivable from species B in an evolutionary sense. This procedure 

 arbitrarily assigns predominant importance to certain characters and is 

 essentiallv the artificial method of classification. It mav be unavoidable, 

 it may even be desirable, but it is not a natural or phylogenetic method, for 

 no organism is advanced or primitive in the sum total of its characters. 

 Though it is possible to arrange organisms in a linear series on such partial 

 grounds, it w^ill not represent their true evolutionary status, except with 

 regard to the characters considered. 



The ditTerence between the evolutionary progression of characters and 

 the actual descent of the plants bearing them was emphasized by Hayata in 

 192 1 and has been well brought out by Zimmermann in the distinction 

 he has drawn between Merkmals Phylogenie and Sippen Phylogenie. The 

 former implies the phvlogenetic arrangement of homologous structures 

 and is a proper subject-matter of comparative morphology. The latter 

 indicates the grouping of organisms in an order of presumed evolutionary 

 descent. Phylogenetic systematists believe that it is legitimate to proceed 

 from the former to the latter, but this Zimmermann and many other 

 botanists will not admit. To take an example; morphologists may claim 

 that the sympetalous corolla is more advanced than the apopetalous corolla 

 and that it is right to presume that the former condition has been evolved 



