NATURAL SELECTION 89 



sometimes reappear in the third and fifth generations 

 after having lain latent in the second and fourth in 

 the case of certain diseases that attack man. There 

 are those who assert that an inherited fatal disease, 

 though passing over alternate generations, pursues 

 the family of the person in whom it first appeared, 

 until all its members are, in the course of a few 

 generations, killed off by it. But this statement 

 rests upon no substantial basis. Marriage into healthy 

 families first checks, and then kills off the disease, owing 

 to its being extruded by healthier elements. 



When we consider that in Nature's wild haunts 

 individuals who possess similar variations are but a 

 few in a crowd, and that similarity of variation acts 

 in no way as a means of bringing the sexes together, it 

 becomes obvious that the pairing of two similarly 

 varied individuals must very rarely take place. If, 

 however, such a marriage did take place, remembering 

 that only one pair survives out of all the progeny 

 of a pair for a generation, it would indeed be 

 passing strange if one of the surviving pair found a 

 mate individually varied like itself. That the same 

 thing should occur a third time in succession would 

 enter into the sphere of the miraculous. But Darwin 

 maintains that nothing is too hard for his potent 

 principle of Natural Selection, and that in some way 

 or other, which he does not explain, it brings about 

 a sufficient amount of pairing to accumulate the 

 desired variations towards the genesis of a new species. 

 But where does the selective principle come in, and 



