BI-PARENTAL REPRODUCTION 73 



apparently a case of reversion to a character formerly pos- 

 sessed by some ancient progenitor of the family." 1 



127. "I have been informed by Mr. B. P. Brent, that he 

 crossed a white Aylesbury drake and a black so-called Lab- 

 rador duck, both of which are true breeds, and he obtained a 

 young drake closely like the Mallard (A. boschas). Of the 

 Musk-duck (A. moschata, Linn.) there are two sub-breeds, 

 namely, white and slate-coloured ; and these I am informed 

 breed true. But the Rev. W. D. Fox tells me that by 

 putting a white drake to a slate-coloured duck, black birds, 

 pied with white like the wild musk-duck, were always 

 produced." 2 



128. " When flowers which have normally an irregular 

 structure become regular or peloric, the change is generally 

 looked at by botanists as a return to the primitive state. 

 But Dr. Maxwell Masters, who has ably discussed this subject, 

 remarks that when, for instance, all the sepals of a Tropseolum 

 become green, and of the same shape, instead of being coloured 

 with one prolonged into a spur, or when all the petals of a 

 Linaria become simple and regular, such cases may be due 

 merely to an arrest of development ; 3 for in these flowers the 

 organs in their earliest conditions are symmetrical, and if 

 arrested at this stage of their growth, they would not become 

 irregular. If, moreover, the arrest were to take place at a 

 still earlier period of development, the result would be a 

 simple tuft of green leaves ; and no one would probably call 

 this a case of reversion. 4 . . . On the doctrine that peloria is 

 simply the result of an arrest of development, it is difficult to 

 understand how an organ arrested at a very early period of 

 growth should acquire its full functional perfection ; how a 

 petal supposed to be thus arrested should acquire its brilliant 

 colours, and serve as an envelope to the flower, or a stamen 

 produce sufficient pollen ; yet this occurs with many peloric 

 flowers. 5 That pelolism is not due to mere chance variability, 

 but either to an arrest of development or to reversion, we 

 may infer from an observation made by Ch. Morren, namely, 

 that families that have irregular flowers often return by 

 these monstrous growths to their regular form ; whilst we 



1 Animals and Plants, vol. ii., p. 14. 2 Op. cit. y pp. 14, 15. 



3 According to the doctrine the present writer is striving to make 

 clear, all reversion is an arrest of development, inasmuch as it is a 

 failure in recapitulation. 



1 But this is just what it is. 



6 The difficulty disappears when we remember that reversion does not 

 necessarily include all characters. A flower may revert in shape while it 

 remains true in colour. 



