x SEX 97 



are concerned has been recently worked out in 

 poultry. The Silky breed of fowls is characterised 

 among other peculiarities by a remarkable abundance 

 of melanic pigment. The skin is dull black, while 

 the comb and wattles are of a deep purple colour 

 contrasting sharply with the white plumage (PI. 

 V., 3). Dissection shows that this black pigment 

 is widely spread throughout the body, being especially 

 marked in such membranes as the mesenteries, the 

 periosteum, and the pia mater surrounding the brain. 

 It also occurs in the connective tissues among the 

 muscles. In the Brown Leghorn, on the other 

 hand, this pigment is not found. Reciprocal crosses 

 between these two breeds gave a remarkable differ- 

 ence in result. A cross between the Silky hen and 

 the Brown Leghorn Silky B rown Leghorn 



cock produced F a birds, * x * 



in which both sexes 

 exhibited only traces 



of the pigment. On <j> X G? F, 



casual observation they 



might have passed for i 1 A A F 



unpigmented birds, for 



with the exception of FlG - I9> 



i n 1 r Scheme illustrating the result of crossing a 



an OCCaSlOnal tleCk OI silky hen with a Brown Leghorn cock. 



, , i Black sex signs denote deeply pigmented 



pigment tneir SKin, birds, and light sex signs those without 



, , , , , pigmentation. The light signs with a 



COmb, and Wattles Were y^k dot in the centre denote birds with 



i ,1 -n _ a small amount of pigment. 



as clear as m the Brown 



Leghorn (PI. V., i and 4). Dissection revealed the 

 presence of a slight amount of internal pigment. 

 Such birds bred together gave some offspring with 

 the full pigmentation of the Silky, some without any 

 pigment, and others showing different degrees of 



H 



