CHAPTER XII 



SOME TEST CASES BETWEEN THE 

 RIVAL THEORIES 



C. TAXONOMIC 



JL HESE cases might equally well go under morphology, for 

 taxonomy or systematic relationship is founded upon that sub- 

 ject. The separation is simply used to prevent the morphological 

 chapter from growing too large. 



It is of interest to note how easily the axioms of taxonomy 

 that are given by Darwin in the Origin of Species are explained 

 by the theory of differentiation. The first one, for example, 



Wide-ranging, much diffused and common species vary most 



fits in admirablv with much that has been said above, and with 

 what the writer hopes to bring out in another book. It should 

 also be compared with Guppy's remarks about the wide-ranging 

 species that so often accompany endemics, and with what is to be 

 said about the wide-ranging species that so often do the same 

 thing in India (p. 158). One may also refer to what will be said 

 about contour maps (p. 149). 



The current view is that the large and widely distributed 

 genera and species are the "successful" ones, and that they are 

 breaking up into new species by the formation of what as yet are 

 only small varieties. On the view taken by the adherents of 

 Darwinism, the Linnean species of the taxonomist is an abstrac- 

 tion, consisting of an agglomeration of smaller forms that really 

 breed true, and that may be more or less well assembled into a 

 Linnean species which can be reasonably well marked off from 

 others that are closely related to it. But upon the theory of dif- 

 ferentiation the case is turned the other way round. There is little 

 or no doubt that many of the very local endemic species, which 

 are often supposed to be relics, but which upon the theory of age 

 and area are regarded as young beginners, are well and clearly 

 marked Linnean species. Take, for example, the Coleus elongatus 

 (p. 24), or the Indian local species described on p. 159. The whole 

 species, in cases like the Coleus, is made up of so few individuals 

 that it is impossible that there should be a great range of varia- 

 tion, for mere lack of numbers. It is after the formation of the 



I 



