CHASTER : SPECIES AND VARIATION. 23 



of these groups would constitute a distinct species. Indeed from 

 the purely morphological point of view this method of procedure is 

 less open to objection than any other. It imposes no artificial limits 

 on the degree of variability of a species, it postulates no conditions 

 of ancestry, it makes no demands that are theoretically incapable 

 of demonstration. In actual practice we might of course be liable 

 to make several species out of a single group owing to the failure 

 to obtain the connecting gradation forms. 



But quite apart from this possibility we must constantly bear in 

 mind the fact that intermediate gradations may no longer exist 

 between two groups of one species. Homo sapiens^ the best known and 

 most attentively studied species of all organized beings, affords such an 

 example. In the Innuit or Eskimo race we find a group of human 

 beings quite distinct from any other. Even the affinities of this race 

 are doubtful. If an analogous case occtirred in the mollusca there 

 would be no hesitation about recognizing a well marked specific, 

 possibly a generic, distinction. But in the case of mankind I need 

 not enter into any lengthy argument against specific subdivision. 

 Man as a species often supplies admirable data for perfectly sound 

 analogy and comparison when discussing such matters as these. 



That within the limits of one species there may be forms sharply 

 marked off from and quite unconnected by intervening gradations 

 with this type need occasion little surprise if we give the matter 

 a few moments' consideration. Were an area of land to be cut off 

 from a continent or were an island to receive one single immigration 

 of a species we should expect that in the course of time the 

 different environmental conditions to which this colony is subjected 

 would result in the production of differences constantly becoming 

 more and more marked. The subject of island faunas is so inter- 

 esting and so important that it demands more than a mere cursory 

 mention. I cannot do better than quote in abbreviated form some 

 of Darwin's classical observations on the fauna and flora of the 

 Galapagos Islands. As everyone knows it was largely owing to a 

 consideration of the remarkable conditions of animal and plant life 

 he observed on these islands that he eventually produced his epoch- 

 making book the " Origin of Species." 



He wrote as follows : " The natural history of these islands is 

 eminently curious . . Most of the organic productions are 

 aboriginal creations, found nowhere else . . yet all show a 

 marked relationship with those of America. Considering the small 

 size of the islands we feel the more astonished at the number of 

 their aboriginal beings. Seeing every height crowned with its crater, 

 and the boundaries of most of the lava streams still distinct, we are 

 led to believe that within a period, geologically recent, the unbroken 



