( XXX vii ) 



auothcr have a different stamling iu classification from the non-geographical 

 entities. 



(2) If a small proportion of the specimens of A' and A^ are the same, 

 and A' and A^ (or one of them) are brought under conditions which favour 

 the appearance of the characters of this small proportion in each case, ' 

 Lionomics teach us that A^ and A^ will in the course of time become more and 

 more similar, overlap wider and wider, and become finally identical. Tliat is 

 to say. A' and A- cannot live together without fusion. However, if A^ and 

 A-, which diff'er, say, in !i9-9 per cent, of the individuals, cannot exist together 

 as separate entities, A- and A', which are connected by intergradation in the 

 intermediate countries, or A^ and A'', of which the ranges of variation are 

 contiguous, or A^ and A*, which are separated by a small gap, have no chance 

 of remaining separate entities, if by accident brought under the same con- 

 ditions of life. As there is a gradation in the morphological difference between 

 geographical representatives (see Fig. 2, in which the curves D', D", D', etc., are 



the geographical representatives), some being sliglitly, others more distinctly, 

 and others again widely different, it is obvious that the chance of the 

 representatives not overlapping in characters, under those altered conditions 

 of life above referred to, becomes larger and larger, the wider the morphological 

 gap is lietween them. From ttiis point of view it depends, therefore, entirely 

 upon the characters of the geographical representatives whether these can 

 exist together or not, i.e. whether there is a similar gap between A' and A- 

 to that between A' and B'. In other words, considering the gradation in 

 the morphological difierences, there are morphologically different geographical 

 re])resentatives which can certainly not exist together without fusing to one 

 entity, and there are others whicli may be so far settled in tlieir characters 

 that a fusion will not take j)lace. 



From what we iiavf said it follows tliat it is wrong to treat all 

 geographical corporeally different forms indiscriminately as being separated by 

 that same barrier wliich prevents synoecic animals from fusing. As science 

 does not knowingly perpetuate errors, the contention which we have 

 demonstrated to be erroneous shonld be abandoned bv those who claim their 



