436 PROGRESS OF SCIENCE IN THE CENTURY. 



first that two parents usually produce many more 

 than a pair of children, and the population thus 

 tends to outrun the means of subsistence; and, 

 secondly, because organisms are at the best only rela- 

 tively well-adapted to their conditions, which, more- 

 over, are variable. This struggle does not express 

 itself merely as an elbowing and jostling around the 

 platter, but at every point where the effectiveness of 

 the response which the living creature makes to the 

 stimuli playing upon it, is of critical moment. As 

 Darwin said, though many seem to have forgotten, 

 the phrase, '^ struggle for existence '' is used " in a 

 wide and metaphorical sense," including much more 

 than an internecine scramble for the necessities of 

 life, — including, indeed, all endeavours for preser- 

 vation and welfare, not only of the individual, but 

 of the offspring too. In many cases, the struggle for 

 existence both among men and beasts is more fairly 

 described as an endeavour after well-being, and what 

 may have been primarily self-regarding impulses 

 become replaced by others which are distinctively 

 species-maintaining, the self failing to find full reali- 

 sation apart from its kin and society. 



E"ow, in this struggle for existence — manifold in 

 its expression, but never unreal — the relatively less 

 fit forms tend to be eliminated. This does not 

 necessarily mean that they come at once to a violent 

 end, as when locust devours locust or the cold deci- 

 mates the birds in a single night, but often simply 

 that the less fit die before the average time, and are 

 less successful than their neighbours as regards off- 

 spring. But whether the eliminative process be 

 gentle or severe, the result is the same, that the rela- 

 tively more fit tend to survive ; and since many varia- 

 ations (the argument continues) are transmitted 



