INTRODUCTION. »u/ a ^ ,l 



SCOPE AND DUTY OF TAXONOMY. 



Scope. — The essence of taxonomy is clearly indicated by the meaning of the word 

 itself. It denotes the science of arrangement or system, and hence classification. While 

 cataloguing is a part of it, it is a small part only. The naming of new forms is a necessary 

 function of taxonomy, but it should always be incidental to giving them their proper 

 meaning and relationship, and never an end in itself. In the case of plants, the mere 

 recognition of supposed new species in the herbarium hardly merits the term descriptive 

 botany, and it can in no wise be regarded as adequate taxonomic investigation. It has its 

 value, and hence its excuse, in the biological exploration of new and distant countries, 

 but, here as elsewhere, permanent taxonomic results must await the application of statis- 

 tical and experimental methods in the field (Clements, 1905). 



To be both comprehensive and thorough, taxonomy must draw its materials from all 

 other fields, just as it must serve them in turn. While it leans most heavily upon mor- 

 phology, it can not afford to neglect histology and physiology, and it must learn to go 

 hand in hand with ecology and genetics in the future. Indeed, if it is to reflect evolution 

 as accurately as it should, it must regard physiological adjustment as the basic pro- 

 cess, and morphological and histological adaptations as the measurable results. This 

 means that the taxonomist of the future will think in terms of evolutionary processes, 

 and will learn to treat his morphological criteria as dynamic rather than static. 



Relation to ecology and experimental evolution. — As a study of life in its environment, 

 ecology deals with the motive force in evolution, and the experimental study of evolution 

 is essentially ecological in nature. Quantitative ecology deals with the kind and amount 

 of the stimulus initial to change, and likewise measures the corresponding response in 

 terms of function and structure. It thus traces the evolution of new forms in minute 

 detail, in so far as they arise through adaptation or variation, and consequently furnishes 

 the only direct evidence of relationship by descent. It affords the sole method of testing 

 the manifold assumptions of existing taxonomy, and provides the foundation upon which 

 an objective and permanent taxonomy may be reared. If mutations prove to be but 

 major variations in which the environic stimulus is hidden or indirect, it will become 

 possible to study the origin of all new features or forms ecologically, since hybrids are 

 to be regarded as new expressions of old forms. It appears probable that this method 

 can be successfully applied to retracing the origin of existing species or stocks, and with 

 increasing knowledge and skill in experimental manipulation, to repeating the change 

 from a genus into a related one. Since tribes and families are but related phyla of genera, 

 it seems not impossible to pass from one family to another experimentally, especially 

 where the gap is slight, as between Ranunculaceae and Rosaceae, or Borraginaceae 

 and Verbenaceae. In short, experimental and quantitative methods promise to turn 

 taxonomy from a field overgrown with personal opinions to one in which scientific 

 proof is supreme. Such a taxonomy is indispensable to the advance of ecology, and 

 apparently can be attained only by adopting its methods. 



The attitude of the ecologist has already been expressed by Clements (1905:12): 



"Taxonomy is distinct from descriptive botany, which is merely a cataloguing of all known forms, with 

 little regard to development and relationship. The consideration of the latter is peculiarly the problem of 

 taxonomy, but the solution must be sought through experimental evolution. The first task of the latter is 

 to determine the course of modification in related forms, and the relationships existing between them. With 

 this information, taxonomy can group forms according to their rank, i.e., their descent. The same method is 

 applicable to the species of a genus, and, in a less degree, perhaps, to the genera which constitute a family. 

 The use to which it may be put in indicating family relationships will depend largely upon the gap existing 



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