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THE AMERICAN NATURALIST [Vol. LIII 



acters (Paley's argument), and (2) the origin of highly 

 perfected structures and functions which are not be- 

 lieved to be adaptive in the biological sense, at least to 

 the extent of influencing survival. The musical and ar- 

 tistic faculties of man belong to this second class. 



Natural selection, as is well known, provides us with at 

 least a formal explanation of the first class of characters, 

 but not of the second. Lamarckism, with a varying de- 

 gree of plausibility, accounts for the origin of characters 

 belonging to either class. That both of these theories 

 are, in last analysis, theories of selection has been pointed 

 out in section II. 



But the claim is to-day heard on various sides that 

 both natural selection and Lamarckism have broken 

 down completely, and that no other existing evolutionary 

 theories merit serious attention. So impossible is it for 

 some biologists to square the widespread appearance of 

 adaptation in nature with their owii special theories of 

 life that they seek to escape the dilemma by declaring 

 this appearance to be largely illusory. Thus Loeb" 

 tells us : 



While it is possible for forms with moacrato disharinonios to survive, 

 their ])ns>ihle oxi^teiife. As a coMseciuence the cmm-^ of apparent a.lap- 

 hi tniicli th.' saiiK' vein, I )av('iit)or1 writes: 



Oiii' might |)r()lital)ly compare such conclusions as the 

 for-cgoiiig with the findings of Cannon,-''^ based upon the 

 detailed study of certain adaptive mechanisms in man. 

 To most of us the conviction is doubtless irresistible, not 

 that such mechanisms now exist because of their harm- 

 ^■,s^;/r>.s■. but tliat they came into .■\i<teiic'e, step hv step, 

 arroHHf nf fhrir ufllilj/. 



