Chapter I 

 INTRODUCTION 



The purpose of this work is to persuade the community of biologists that the ac- 

 cepted primary classification of living things as two kingdoms, plants and animals, 

 should be abandoned; that the kingdoms of plants and animals are to be given definite 

 limits, and that the organisms excluded from them are to be organized as two other 

 kingdoms. The names of the additional kingdoms, as fixed by generally accepted 

 principles of nomenclature, appear to be respectively Mychota and Protoctista. 



These ideas originated, so far as I am concerned, in the instruction of Edwin 

 Bingham Copeland, my father, who, when I was scarcely of high school age, admitted 

 me to his college course in elementary botany. He thought it right to teach freshmen 

 the fundamental principles of classification. These include the following: 



The kinds of organisms constitute a system of groups; the groups and the system 

 exist in nature, and are to be discovered by man, not devised or constructed. The 

 system is of a definite and peculiar pattern. By every feature of this pattern, we are 

 inductively convinced that the kinds of organisms, the groups, and the system are 

 products of evolution. It is this system that is properly designated the natural system 

 or the natural classification of organisms. It is only by metaphor or ellipsis that these 

 terms can be applied to systems formulated by men and published in books. 



Men have developed a classification of organisms which may be called the taxo- 

 nomic system. Its function — the purpose for which men have constructed it — is to 

 serve as an index to all that is known about organisms. This system is subject to cer- 

 tain conventions which experience has shown to be expedient. Among natural groups, 

 there are intergradations; taxonomic groups are conceived as sharply limited. Natural 

 groups are not of definite grades; taxonomic groups are assigned to grades. When we 

 say that Pisces and Filicineae are classes, we are expressing a fact of human conven- 

 ience, not a fact of nature. The names assigned to groups are obviously conventional. 



Since the taxonomic system represents knowledge, and since knowledge is ad- 

 vancing, this system is inherently subject to change. It is the right and duty of every 

 person who thinks that the taxonomic system can be improved to propose to change 

 it. A salutary convention requires that proposals in taxonomy be unequivocal: one 

 proposes a change by publishing it as in effect; it comes actually into effect in the 

 degree that the generality of students of classification accept it. The changes which 

 are accepted are those which appear to make the taxonomic system, within its conven- 

 tions, a better representation of the natural system. Different presentations of the 

 taxonomic system are related to the natural system as pictures of a tree, by artists of 

 different degrees of skill or of different schools, are related to the actual tree; the 

 taxonomic system is a conventionalized representation of the natural system so far as 

 the natural system is known. 



These statements are intended to make several points. First, as a personal matter, 

 advancement of knowledge of natural classification, and corresponding improvement 

 of the taxonomic system, have been my purpose during the greater part of a normal 

 lifetime. Secondly, I have pursued this purpose, and continue to pursue it, under the 

 guidance of principles which all students of classification will accept (perhaps with 

 variations in the words in which they are stated). In the third place, I have tried to 

 answer the question which scientists other than students of classification, and likewise 

 the laity, are always asking us: why can one not leave accepted classification undis- 



