Chapter IV —57- Origin of Areas 



without anthocyanin, etc. Such parallel forms may arise in different 

 parts of the area of a species either by mutation or in consequence of 

 hereditary causes, due to the parallel variation of the characters of 

 allied forms, which "are apt to vary under similar exciting causes in a 

 similar manner" (Darwin, 1911, p. 585). Such parallel variation, 

 called by Darwin "analogical variation", was later, on the basis of 

 extensive matenal, formulated by Vavilov as the "law of homologous 

 series in variation". But if this may be accepted as regards separate 

 characters, changes in which may be caused by separate factors there 

 is stiU no basis for assuming the possibility of the polytopic origin of 

 species, characterized by a whole complex of characters, since no two 

 localities on earth are exactly alike in all respects, as regards all factors 

 all physico-geographical conditions. In any case, the advocates of the 

 polytopic theory have presented only theoretical assumptions and have 

 not advanced a single real proof. Even when the discontinuity of an 

 area seems inexplicable, we may in most cases expect that geological 

 data will be discovered, if they have not already been discovered, 

 which will explain the configuration of such areas on the basis of 

 purely historical causes. 



References: 



ce„t?ardTFranTeTpaVzurirhT '''""^^ '' '' developpement des floras dans le massif 



(Ann^'SeV^tl^Jd. B^t Genfve'Vol ')" '" "°"'=^»""" ^' '^ ^°^^^ '' ^^ °"S'"- 

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de B^eLTsection^'de B^ioltgrapht)'' "'^"''°" ^^^^'^ '^^ ^^ ^^ ^"^ ^-'^^ ^.ogr. 

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Rosa, D., 1903: Die Progressive Reduktion der Variabilitat Qena). 

 KOSA, D., 1931: L'ologenese (Paris). 



Rend'^Ts^SVTAc'ad.^i'u.^'^.tri'^r'Sf 9^ "' °'^" °' ''''''' ^^"'"^''^^ 



tUrhl^^u'T^'-i^/i^lZ^^l, ^'"i '^f geographisch-morphologische Methode in der systema- 

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