CHAPTER yil. 



'ARGUMENTS FROM DISTRIBUTION". 



§137. In §§105 and 106, we contemplated the phenomena 

 of distribution in Space. The general conclusions reached, 

 in great part based on the evidence brought together by Mr. 

 Darwin, were that, " on the one hand, we have similarly-con- 

 ditioned, and sometimes nearly-adjacent, areas, occupied by 

 quite different Faunas. On the other hand, we have areas 

 remote from each other in latitude, and contrasted in soil as 

 well as climate, which are occupied by closely-allied Faunas." 

 Whence it was inferred that " as like organisms are not uni- 

 versally, or even generally, found in like habitats; nor very 

 unlike organisms, in very unlike habitats ; there is no manifest 

 pre-determined adaptation of the organisms to the habitats." 

 In other words, the facts of distribution in Space do not 

 conform to the hypothesis of design. At the same 



time we saw that " the similar areas peopled by dissimilar 

 forms, are those between which there are impassable barriers ; 

 while the dissimilar areas peopled by similar forms, are those 

 between Avhich there are no such -barriers; " and these 

 generalizations appeared to harmonize with the abundantly- 

 illustrated truth, "that each species of organism tends ever 

 to expand its sphere of existence — to intrude on other areas, 

 other modes of life, other media." 



By way of showing still more clearly the effects of com- 

 petition among races of organisms, let me here add some 

 476 



