Biological Struggle for Existence 2 1 5 



A case of {20), of extreme importance in its effects upon 

 the next generation, is that of the struggle of males for the 

 female, occurring often apparently irrespective of the num- 

 ber of available females. 



The third case of struggle (3) is that in which individ- 

 uals struggle against fate — the inorganic environment — 

 not directly against one another. This is really a * struggle 

 to accommodate' — to reach a state of adjustment or balance 

 under which continued living is possible. As the other 

 forms may perhaps be styled respectively ' struggle to eat ' 

 (in a large sense) and 'struggle to win,' so this may be 

 called * struggle to accommodate,' or * struggle to live.* 

 The distinction between cases (2) and (3) disappears in 

 instances in which the animal accommodates actively in 

 order to coping with his enemies ; for these then become 

 part of his environment in the sense of case (3). 



The relation of large productiveness to this last form (3) 

 of the struggle for existence would seem to be but indirect. 

 It would not matter how many individuals perished pro- 

 vided some lived ; and any amount of overproduction would 

 not help matters if none of the individuals could cope with 

 the environment. Yet on the theory of indeterminate or 

 indefinite variation, the chances — under the law of prob- 

 ability — of the occurrence of any required variation is 

 a definite quantity, and these chances are of course in- 

 creased with large productiveness ; for with more varia- 

 tions, more chances of those that are fit, and with increased 

 production, more variations. No better case in point could 

 be cited than Dallinger's experiments on the effects of 

 changes of temperature on infusoria.^ 



In recent evolution theory the doctrine of natural selec- 



1 An illustration suggested by Professor E. B. Poulton. 



