128 TBLEGONY AND REVERSION. 



different thing may lead to similar results), new strains may- 

 be rapidly produced. Certain well-fixed types of Shetland 

 ponies have been formed by close inbreeding, and similar 

 results might be obtained without the disadvantages which 

 follow inbreeding by judicious selective breeding. For 

 example, if an English thoroughbred mare is mated with a 

 thoroughbred horse whose ancestors for some generations 

 have lived a comparatively natural life — in say Australia or 

 America, — a horse, nevertheless, closely resembling the mare 

 both in his physical and mental characters, the offspring 

 would in all probability present all the striking peculiarities 

 of the parents without any weakening of the constitution 

 such as is apt to follow in and in breeding. But as allow- 

 ance must always be made for variation (especially when 

 forms from widely separated areas are mated), for the 

 appearance of sports in one direction or another, the 

 offspring might very well be an improvement on the 

 parents— give evidence, in fact, of progressive develop- 

 ment in some useful or desired direction, We often use 

 the phrase 'Mike produces like," but we often fail to 

 realise that to give the offspring a chance of being like 

 the parents, the parents or their grandparents must be 

 like each other. It seems to me that, as a rule, progress in 

 any given direction, i. e. progressive development, will 

 only be possible when the parents closely agree with each 

 other in their physical and mental peculiarities. They are, 

 of course, likely to agree when closely related by birth, if 

 their ancestors have been interbred for several genera- 

 tions ; but they may also agree in all essential points when 

 distantly related, or when belonging to quite distinct 

 strains. 



The opposite of mating closely related forms is the 

 crossing of distinct breeds. The result of intercrossing is 

 well known. We are all familiar with the phrase " the 

 swamping effects of intercrossing," which implies that 

 quite the opposite result is obtained from what we arrive 

 at by isolation or inbreeding. Intercrossing, in fact, 

 generally tends to arrest development in any given 



