1 92 1.] Subspecies and Evolntion. 531 



from such experimeuts are of little value in studying evolution 

 in its natural state. Thoy are^ of course, of immense value to 

 the economist or poultry-fancier, hut the artificial perpetua- 

 tion of freaks is surely not a state of which Nature approves. 



Natural selection works at the gradual improvement of 

 life, and the elimination of what is not good, but has to 

 work on certain definite material. Though I realise that 

 every branch of life has great possibilities, there are equally 

 very definite limitations. For instance, the struggle for 

 existence precludes the various branches of life livino- as 

 equals, certain groups always seeking leadership. When 

 such accidents as mutational freaks occur, they spring into 

 the world on their own responsibility, and are variations 

 springing from within, being entirely divorced from environ- 

 ment. If the change is beneficial or harmless, they are 

 allowed to remain and reproduce their freakish variation ; 

 if the change is harmful or a handicap, they die. When 

 man, however, artificially perpetuates harmful freaks, he 

 does so in spite of natural selection. So soon as man with- 

 draws artificial protection and selection, the freak, thrown 

 on the mercy of natural selection, must revert or perish. 

 Such is the law for which we have to be thankful. 



Moreover, it seems that nearly all artificially-produced 

 races, when removed from artificial conditions, do not retain 

 those variations which artificial selection has given them. 

 The feral goats which I have seen in Ireland, Scotland, and 

 on Round Island in the southern Indian Ocean, the feral 

 Pigeon of Mauritius, and the Goldfish which after introduc- 

 tion to Madagascar devoured the only edible freshwater fish 

 in the island, have all tended to revert respectively to v/ild 

 Goat, wild Rock-Pigeon, and the ungainly mud-coloured 

 ancestral stock of the Goldfish. 



This leads me to assume that artificial selection does not 

 (as Mendelians maintain) alter the gamete, unless artificial 

 conditions and selection are maintained for a sufficiently long- 

 period to permit cumulative effect. But mutational variation 

 under natural conditions remains constant, because natural 

 conditions do not appreciably vary. But I admit that the 



