IN-AND-IN BREEDING. 103 



satisfactory results from any union, there should be 

 some inherent, constitutional, or fundamental differ- 

 ence ; some such difference as we often see in the 

 human family to be the ground of preference and at- 

 tachment ; as men generally prefer women of a feminine 

 rather than a masculine type. All desire, in a mate, 

 properties and qualities not possessed by themselves. 

 Now assuming as Mr. Walker holds, that organization 

 is transmitted by halves, and that, in animals of the 

 same variety, either parent may give either series of 

 organs, we can see in the case of brother and sister 

 that if one receives the locomotive system of the father 

 and the nutritive system of the mother, and the other 

 the locomotive system of the mother and the nutritive 

 system of the father, they are essentially unlike, there 

 is scarcely any similarity between them, although, as 

 we say, of precisely the same blood ; and their progeny 

 if coupled might show no deterioration ; whereas, if 

 both have the same series of organs from the same 

 parents, they would be essentially the same, a sort of 

 quasi identity would exist between them, and they are 

 utterly unfit to be mated. There might be impotency, 

 or barrenness, or the progeny, if any, would be decid- 

 edly inferior to the parents ; and the same applies, more 

 or less, to other relatives descended from a common 



ancestry, but more distant than brother and sister. 

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