GENEKAL INTRODUCTION. XXlX 



It will be remembered that Weismanu tliought it very 

 probable that Darwin's barb-fantail-spot cross was 

 ** essentially a mere case of reversion as regards the 

 coloration of the plumage." In my owl-archangel- 

 fantail cross there is not only more complete reversion 

 as regards the coloration than in Darwin^s cross-bred 

 bird ; there is, as far as exteimal measurements can show, 

 practically complete reversion as regards form, but more 

 remarkable still, there appears to be reversion as regards 

 the constitution and habits. 



A successful and experienced breeder of sporting dogs 

 recently told me that close inbreeding for three or four 

 generations leads to marked senile degeneration. If, 

 however, there are any puppies in a grossly inbred litter 

 that take after a good ancestor several generations re- 

 moved, they invariably prove the strongest and best. 

 In the same way it is said that if an inbred sire and 

 dam produce a striped dun-coloured foal, it almost 

 always turns out well, and alike in hardiness, staying 

 power, and durability eventually surpasses closely re- 

 lated offspring of a grey, chestnut, or bay colour. That 

 highly bred, not very fertile, delicately nurtured parents, 

 with weak constitutions, should sometimes give rise to 

 vigorous prolific hardy offspring may seem impossible, 

 and yet a great many facts might be marshalled in sup- 

 port of this assumption. Reversion, in fact, seems to 

 lead to a form of rejuvenescence — due presumably to the 

 ancestral imits overcoming and controlling the more re- 

 cently evolved and less stable units, which, if allowed to 

 have their way, would give rise to offspring bearing all 

 the marks of decadence that characterised the immediate 

 ancestors. 



My "restored" blue rock looks as vigorous and hardy 

 and compact as a wild bird, and he is greatly admired by 

 fanciers alike for his carriage, form, and colour. He 

 seems to prefer sitting, when off duty, in a dark recess to 

 sunning himself, and alike in his movements and disposi- 

 tion he differs from his companions. He is shy, active 

 in his movements, and when disturbed seems to be not a 



