198 The Science of Life. 



petition, e.g. in the reaction of solitary animals to a 

 change of environment ; (c) the manifold facts of life to 

 which some such word as altruism must be applied; 

 and (d) the applicability of the general idea to parts 

 within the organism, or to such processes as the race 

 of many spermatozoa towards one ovum, we recognize 

 that the phrase " struggle for existence " must be taken 

 as a technical expression of what occurs whenever the 

 effectiveness of an organic response is of critical mo- 

 ment in relation to continuance, welfare, and evolution. 

 In other words, the broadening and deepening of the 

 idea of struggle one of the features of post-Darwinian 

 biology leads us to recognize that progress depends on 

 much more than a squabble around the platter; that 

 the struggle for existence is far more than an inter- 

 necine struggle at the margin of subsistence; that it 

 includes all the multitudinous efforts for self and for 

 others between the poles of love and hunger; that it 

 comprises all the endeavours of mate for mate, of parent 

 for offspring, of kin for kin; that love and life are 

 factors in progress as well as pain and death; that life 

 for many an animal means the well-being of a socially- 

 bound or kin-bound organism in a social milieu] that 

 egoism is not satisfied until it becomes altruistic. 



Chapter XV. 

 Psychology of Animals. 



Biology and Psychology Theological Interpretation Metaphysical In- 

 terpretation Animal Automatism The Word "Instinct" The 

 Inclined Plane of Activities Lamarckian Theory of Instinct Dar- 

 win's Position The Work of Romanes Weismanris Position 

 Lloyd Morgan! s Experiments Open Questions Psychological Aspects 

 of Mating. 



From early times men have interested themselves in 

 what may be called the mental life of animals, but, 

 excepting Descartes, there was little attempt at scientific 



