326 Geographical Distribution of Animals 



different from that which was upheld by L. Agassiz. As Murray 

 himself puts it : " To my multiple origin, communication and direct 

 derivation is essential. The species is compounded of many influences 

 brought together through many individuals, and distilled by Nature 

 into one species ; and, being once established it may roam and spread 

 wherever it finds the conditions of life not materially different from 

 those of its original centre 1 ." This declaration fairly agrees with 

 more modern views, and it must be borne in mind that the application 

 of the single-centre principle to the genera, families and larger groups 

 in the search for descent inevitably leads to one creative centre for the 

 whole animal kingdom, a condition as unwarrantable as the myth of 

 Adam and Eve being the first representatives of Mankind. 



It looks as if it had required almost ten years for The Origin of 

 Species to show its full effect, since the year 1868 marks the publica- 

 tion of Haeckel's Natiirliche ScJwepfnngsgeschichte, in addition to 

 other great works. The terms Oecology (the relation of organisms 

 to their environment) and Chorology (their distribution in space) 

 had been given us in his Getter die Morphologie in 1866. The 

 fourteenth chapter of the History of Creation is devoted to the 

 distribution of organisms, their chorology, with the emphatic asser- 

 tion that " not until Darwin can chorology be spoken of as a separate 

 science, since he supplied the acting causes for the elucidation of the 

 hitherto accumulated mass of facts." A map (a "hypothetical sketch ") 

 shows the monophyletic origin and the routes of distribution of Man. 



Natural Selection may be all-mighty, all-sufficient, but it requires 

 time, so much that the countless aeons required for the evolution of 

 the present fauna were soon felt to be one of the most serious draw- 

 backs of the theory. Therefore every help to ease and shorten this 

 process should have been welcomed. In 1868 M. Wagner 2 came to 



1 Murray, The Geographical Distribution of Mammals, p. 14. London, 1866. 



2 The first to formulate clearly the fundamental idea of a theory of migration and its 

 importance in the origin of new species was L. von Buch, who in his Physikalische 

 Beschreibung der Canarischen Inseln, written in 1825, wrote as follows: "Upon the con- 

 tinents the individuals of the genera by spreading far, form, through differences of the 

 locality, food and soil, varieties which finally become constant as new species, since owing 

 to the distances they could never be crossed with other varieties and thus be brought back 

 to the main type. Next they may again, perhaps upon different roads, return to the old 

 home where they find the old type likewise changed, both having become so different that 

 they can interbreed no longer. Not so upon islands, where the individuals shut up in 

 narrow valleys or within narrow districts, can always meet one another and thereby 

 destroy every new attempt towards the fixing of a new variety." Clearly von Buch explains 

 here why island types remain fixed, and why these types themselves have become so 

 different from their continental congeners. Actually von Buch is aware of a most 

 important point, the difference in the process of development which exists between a new 

 epecies 6, which is the result of an ancestral species a having itself changed into b and 

 thereby vanished itself, and a new species c which arose through separation out of the 

 same ancestral a, which itself persists as such unaltered. Von Buch's prophetic view seems 

 to have escaped Lyell's and even Wagner's notice. 



