80 DARWINISM AND HUMAN LIFE 



these great and sudden changes frequent in many 

 regions of the earth ; but it is not often they 

 present themselves so vividly as in the foregoing 

 instance, for here, scene after scene, is one of 

 Nature's silent, passionless tragedies open before 

 us, countless myriads of highly organised beings 

 rising into existence only to perish almost im- 

 mediately, scarcely a hard-pressed remnant re- 

 maining after the great reaction to continue the 

 species." 



KEASONS FOR THE STRUGGLE FOR EXISTENCE. 

 The reasons for the struggle for existence among 

 animals and plants are fundamentally the same 

 as those which lie behind our own human struggle 

 and endeavour. " Why do the people thus strive 

 and cry ? " Goethe asked, and gave the answer, 

 " They will have food, they will have children, 

 and bring them up as well as they can." So it 

 is with other living creatures their twofold, 

 never-ending business is to care for themselves 

 and to care for others. It has been said that 

 hunger and love solve the world's problems, and 

 this is true if we take a wide enough view of these 

 notable words. 



(a) One reason for struggle is to be found in the 

 tendency to over-population. The river of life 

 is always tending to overflow its banks. Struggle 

 is the safety-valve against the internal pressure 

 of rapidly increasing population. Wallace quotes 

 Kerner to the effect that a common British weed 

 (Sisymbrium sophia) often has three-quarters of 

 a million seeds ; if all grew to maturity for only 

 three years the whole of the land-surface of the 

 globe would not hold them. An annual plant 

 with only two seeds would be represented by 



