HEEEDITY, YAEIATION" 133 



enemies whicli had been attracted by their inordinate num- 

 berSj till the former balance of life is restored, and the rapid 

 powers of increase of the sufferers soon restores them to their 

 normal population. It is against the adverse powers of inor- 

 ganic nature that speedy reproduction is such a safe-guard. 

 When fire or flood, droughts or volcanic outbursts have de- 

 stroyed animal life over wide areas, the few survivors on the 

 margin of the devastated area are able to keep pace with 

 renewed vegetation and again stock the land with its former 

 variety of living things. 



The facts outlined in the present chapter, of abundant and 

 ever-present variability with enormous rapidity of increase, 

 furnish a sufficient reply to those ill-informed writers who still 

 keep up the parrot-cry that the Darwinian theory is insuffi- 

 cient to explain the formation of new species by survival of 

 the fittest. 



They also serve to rule out of court, as hopelessly inefficient, 

 the modern theories of ^' mutation " and " mendelism,'' which 

 depend upon such comparatively rare phenomena as " sports '' 

 and abnormalities, and are, therefore, ludicrously inadequate 

 as substitutes for the Darwinian factors in the world-wide and 

 ever-acting processes of the preservation and continuous adap- 

 tation of all living things. The phenomena upon which these 

 theories are founded seem to me to be mere insifmificant bve- 

 products of heredity, and to be essentially rather self-destruc- 

 tive than preservative. They form one of nature's methods of 

 getting rid of abnormal and injurious variations. The per- 

 sistency of Mendelian characters is the veiy opposite of what 

 is needed amid the ever-changing conditions of nature.^ 



1 A critical examination of these theories is gjiven in Mr. G. Archdall 

 Reid's recent work, The Principles of Heredity. There is also a shorter and 

 more popular criticism in the Introduction to Professor E. B. Poiilton's 

 Essays on Evolution (1908). 



