SINGLE COMB LEGHORN AND ROSE-COMB MINORCA. 29 



as it does in Series II to white ; mottling is recessive to solid color. The 

 comb, crest, muffling, and extra toe are inherited essentially as in Series II. 

 Striking is the nearly universal imperfection of dominance. 



Series IV, —Single-comb White Leghorn and Rose-comb Blacl< Minorca. 

 STATEMENT OF PROBLEM. 

 This cross was undertaken to learn the inheritance in these races of the 

 characteristics described below. 



THE R.4CES AS .^ WHOLE. 



The Leghorn has been described at page i8 ; the Minorca at page 6. 



TABLE OF CHARACTERISTICS. 



REMARKS ON THE CHAR.ICTERISTICS. 



1. General Plumage Color. — Black is one of the constituents of the 

 color of Gallus bankiva, being the chief color of the breast. Just how a 

 wholly black condition of plumage was attained is of course not exactly 

 known ; there are, however, many instances known of melanic sports among 

 birds. It is probable that wholly black varieties have arisen as a result of 

 excessive production of the black pigment, melanin. 



2. Comb Form. — The rose comb is a broad mass of erectile tissue replacing 

 the single comb. Anteriorly it overhangs the nostrils and extends over and 

 back of the eyes. The upper surface is covered bj' numerous tubercles. 

 These do not, in young birds and females, run wholly at random but tend to 

 lie in five or more parallel lines. Posteriorly the rose comb ends in a finger- 

 like process or spike. The rose comb is the last term of the series starting 

 at the single comb and having the triple or pea comb for its middle term. 



3. Foot Color. — The dense black color of the scutes of the foot of the 

 Minorca constitutes a positive or additive characteristic as contrasted with 

 the pigmentless condition of the yellow-footed White lyCghorn. 



M.\TERIAL. 



As mothers three White Leghorns were used, of unknown ancestry but 

 reputed pure. They had fair Leghorn points except as noted in the descrip- 

 tions given below. When mated with White Leghorn 13.1 S they produced 

 only white offspring. 



IDA. Feathers all white ; comb strictly single. 



