1 30 J. HOPKINSON — ANNITEESAEY ADDRESS : 



Darwin demonstrated what others vaguely believed or dimly saw — 

 the course and methods of biologic evolution. Darwin gave hope 

 to philosophy. . . . By his discoveries the discoveries of all other 

 biologists have been correlated and woven into systematic phi- 

 losophy." 



But progress is not universal ; lowly forms of life still exist ; 

 and some creatures are degenerate representatives of once higher 

 forms. Living things seldom voluntarily " seek fresh woods and 

 pastures new ; " they are driven to do so because they tend to 

 increase faster than their wants can be supplied. Either there is 

 not room for all or thei'e is not food for all. But if not for all, 

 there is for some, and so long as any can continue to exist without 

 a struggle, some will continue to exist without modification, and 

 the longer they do so, the more stable will their forms become, 

 their fixity of type being strengthened by inheritance. Then if 

 external conditions become simpler, degeneration may ensue owing 

 to the disuse of certain organs. Thus there may be two varieties 

 of the same species of animal existing near together at the same 

 time, one of which possesses the sense of sight and the other does 

 not. One, for instance, may live at the mouth of a cave where the 

 power of vision is of advantage, therefore retaining its sight ; the 

 other may live in the interior of the cave where sight is useless, 

 therefore becoming blind through the disuse of its eyes for many 

 generations. Again, those species which continue to live because 

 their weaker brethren have succumbed, and those which have been 

 driven away from their ancestral home, will become more vigorous, 

 or will acquire more adaptability to changing cii'cumstances, and 

 these qualities will be strengthened by heredity. Herein we see 

 why the rarer species are usually well differentiated, and the 

 commoner species are usiially prolific in varieties through which 

 they insensibly run one into another. The struggle for existence 

 being far more keen between diiferent individuals of the same 

 species than it is between individuals of different species, the rarer 

 a species is, the less has it to struggle with other individuals of its 

 own species, and the more stable does it become in character : the 

 commoner a species is, the greater is its struggle, and the more 

 variable and adaptive does it become. 



Natural selection must, however, have variations to act upon. 

 It does not beget them. Variability is probably as much an innate 

 tendency in living things as is heredity. Each strives for mastery 

 over the other, and there is no more difficulty in crediting the 

 plastic or fonnative action of the one than that of the other. 

 The difiiculty really lies ia our conception of the nature of life. 



