258 THE CROSSING, &C, OF PIGEONS AND FOWLS. 



these Bantams. I have seen Silver Bantams, directly 

 descended from his stock, which had become almost 

 as barren as hybrids; for, not a single chicken had 

 been, that year, hatched from two full nests of eggs." 



The proofs, which we advance, of the truth of the 

 theory of Reversion, are, viz., the fact, that, with all 

 of the individuals, which are most wanting in the 

 characters of their respective species, there is the 

 greatest evil, from close-interbreeding; and, the fact, 

 that, with all of the individual animals or plants 

 which most approximate full and proportionate devel- 

 opment, there is the least degree of such evil. But; 

 taking a single instance, there is none which presents 

 such a delicate, crucial test of the truth of the theory 

 of reversion, as the following remarkable case. The 

 animal, mentioned below, advances, in but the slight- 

 est appreciable degree, to the perfect type of its 

 species; yet, Darwin, who is wholly ignorant of the 

 cause of the effect which he records, has remarked 

 the physiological gain, which accompanies the slight, 

 structural regain. 



He says (p. 154, Vol. ii, Animals and Plants, &c): 



"I have noticed, as a general rule, that even the 

 slightest deviation from feminine character, in the 

 tail of the male Sebright (Fowl) — say, the elonga- 

 tion, by only a half an inch, of the two principal tail- 

 feathers (/) — brings with it improved probability of in- 

 creased fertility /" 



In a note, to page 155, Vol. ii, Animals and Plants, 

 &c, Darwin says: 



"See also the 'Poultry Book,' by Tegetmeier, 1866, 



