vii HEREDITY, VARIATION 123 



beings rising into existence only to perish almost immediately, 

 scarcely a hard-pressed remnant surviving to continue the species." 



It may, however, be concluded that not thus are species 

 exterminated in any region that remains suitable for their 

 existence. Long before they approach extinction, the very 

 scarcity of them drives away, one after another, the crowd 

 of enemies which had been attracted by their inordinate 

 numbers, 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 inorganic nature that speedy reproduction is such a safe- 

 guard. When fire or flood, droughts or volcanic outbursts 

 have destroyed 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 insufficient 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 " Mendel- 

 ism," 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 adaptation of all living things. The pheno- 

 mena upon which these theories are founded seem to me to 

 be mere insignificant by-products of heredity, and to be 

 essentially rather self- destructive than preservative. They 

 form one of nature's methods of getting rid of abnormal and 

 injurious variations. The persistency of Mendelian characters 

 is the very opposite of what is needed amid the ever-changing 

 conditions of nature. 1 



1 A critical examination of these theories is given 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. Poulton's Essays on 

 Evolution (1908). 



