THE CROSSING, &C, OP PIGEONS AND FOWLS. 263 



cause of which is wholly undreamt of in his philoso- 

 phy, — that such is the case. 



Says he, p. 236, Vol. i, Animals and Plants, &c: 



"MM. Boitard and Corbie affirm, after their great 

 experience, that, with crossed pigeons, the more distinct 

 the breeds, the more productive are their mongrel off- 

 spring!' (!) 



The above quotation furnishes the key to the whole 

 mystery of the good resulting from crossing. Apply 

 this rule, to all of the many millions of animals of every 

 species, and it will be found, that the increased good 

 from crossing, is in proportion to the amount of posi- 

 tive characters, of the given species, which have been 

 supplied, to fill a want, existing in either parent. 



Darwin says : 



"Varieties, however much they differ from each 

 other in external appearance, cross with perfect facility, 

 and yield perfectly fertile offspring" (p. 326, Origin of 

 Species). 



Aye; and, as he states above, the more that they 

 differ, the greater is the increase of fertility, when 

 crossed. 



"The perfect fertility of so many domestic varieties, 

 differing widely from each other in appearance, for in- 

 stance, as those of the Pigeon, or those of the cabbage, 

 is a remarkable fact; more especially, when we re- 

 flect how many species there are, which, though re- 

 sembling each other most closely, are utterly sterile 

 when crossed" (p. 327, Origin of Species). 1 



Now, would any suspect, from the bland manner in 

 which this last observation is made, that the obvious 

 and admitted significance of the fact of the sterility of 



