I THE DARWIN CENTENARY. [February 5, 



no causal explanation, but merely restate the mystery in terms of 

 perfecting principles or entelechies, and those which find the causes 

 of adaptations in unknown laws of variation, there remain two 

 attempted explanations of organic fitness which may be known by 

 the general terms of Lamarckism and Darwinism. Lamarckism is 

 a theory which attempts to explain racial adaptations as the result 

 of the inheritance of individual, acquired adaptations. It is well 

 known that extrinsic and intrinsic changes frequently produce adap- 

 tive modifications in organisms, and Lamarckism maintains that 

 these individual, somatic modifications are ultimately inherited and 

 that in this way adaptations, characteristic of a race or species, 

 arise. Thus all inherent or germinal adaptations are supposed to 

 be derived from acquired or somatic ones. How these individual 

 somatic adaptations arise in the first place Lamarckism does not 

 undertake to explain; the adaptive character of the response of an 

 organism to its environment, to use and disuse, and to its needs, 

 remains as much of a mystery as ever. As we know Darwin be- 

 lieved that some individual adaptations, especially those which 

 resulted from the use or disuse of parts, might be inherited and thus 

 become racial or specific. This theory if true would afford a good 

 explanation of inherited adaptedness; unfortunately there is no evi- 

 dence that such acquired adaptations are regularly inherited. For 

 years this evidence has been earnestly sought but no such confirma- 

 tions have been found as would certainly have been the case if this 

 kind of inheritance were at all common. 



Modern Darwinism, on the other hand, rejects the possibility of 

 the inheritance of such acquired adaptations, and maintains that 

 there is no genetic connection between acquired and inherent fitness. 

 It maintains that all adaptations are due to multifarous variations 

 among offspring and the elimination by natural selection of those 

 which are poorly adapted. All adaptations which are for the good 

 of the species rather than of the individual, admit of no other nat- 

 ural explanation ; such adaptations could not have arisen from adap- 

 tations acquired by an individual as Lamarckians assume, since they 

 benefit the species at the expense of the individual. Darwin showed 

 in masterly manner that the continual elimination of the unfit and 

 the preservation of favored races would gradually improve the stan- 



