THE CATEGORIES OF VARIANT INDIVIDUALS 59 



terms or are only rarely used by systematists. But, although 

 the majority of systematists still maintain the traditional 

 Linnean categories, many feel impelled to supplement them 

 with other terms devised to fit special groups revealed by 

 systematic analysis or to attempt to substitute for the older 

 categories of species and varieties fresh ones designed to bring 

 systematic procedure into line with new methods of analysis, 

 (e.g. Linneon and Jordanon (Lotsy), ' Formenkreise ' and 

 ' Rassenkreise ' (Kleinschmidt, Rensch) ) . 



The following appear to be the chief types of category 

 that have been proposed : 



Taxonomic. 



Palaontological (lineage, gens). 



Geographical (local race, colony, ' Rassenkreis '). 



Genetical and Reproductive (e.g. pure line, biotype, clone, 

 syngameon, sibship). 



Physiological (strain, physiological race). 



Although for the purpose of convenient discussion we have 

 adopted the above distinctions, it will be noticed that a hard 

 and fast division between, e.g., genetical and geographical 

 categories is fundamentally arbitrary. All we wish to imply 

 by these distinctions is that various methods of research have 

 led to the adoption of various categories which we have to 

 define and relate one to another. 



Over and above these we have the various terms which 

 perhaps could be classed as genetical by which heritability, 

 partial heritability or non-heritability is implied, such as 

 forma, alteration, Dauermodifikation, genotype and phenotype. 

 There is also a category of groups, partly of geographical, 

 partly of habitudinal significance such as the school, rookery, 

 shoal, etc. Some categories are based on more than one 

 concept, e.g. the ecotype, and ecospecies are groups recognised 

 on account of genetical behaviour and ecological relationship. 

 Lastly we may point out that some categories are strictly 

 classificatory, i.e. they form part of a system and designate 

 a more or less closed group, though they are not all in current 

 taxonomic use, while others, such as lineage, are taxonomically 

 neutral, i.e. they involve no recognition of a classificatory 

 system. Of the same order is the term population or 

 natural population, which is used to designate any number 

 of closely related and interbreeding individuals occupying 



