R. C. PUNNETT AND THE LATE MaJOR P. G. BaILEY 287 



The four types of down appeared as follows : 



Black Choc. Br. Str. Gold 



17 36 30 38 



Reckoning one-third of the chocolates as blacks our ratio of blacks : non- 

 blacks in respect of plumage becomes 17 + 12 = 29 : 92. The blacks form 

 almost exactly the quarter of the total that theory demands. 



Where black plumage depends upon two factors, as in this cross, it is 

 clear that an association between egg tint and plumage colour would 

 be less easy to demonstrate statistically, even should it occur. In Figs. 

 10 and 11 the F^ blacks and non-blacks have been set out with reference 



.!«..n!l.. 



1 234 56 7 89 10 11 



Fig. 10. Distribution of grades of egg-colour in black Fg birds 

 ex Langshan ^ x Hamburgh ^ . 



I : 



lii 



1234 56789 10 11 



Fig. 11. Distribution of grades of egg-colour in brown and gold birds of 



F2 generation ex Langshan $ x Hamburgh ^ . 



to the egg-colour. So far as they go the two curves are obviously of a 

 similar nature, and there is no reason for supposing that any factor 

 influencing egg-colour is here associated with blackness of the plumage. 



Broodiness. 



Our data regarding broodiness are less satisfactory than those con- 

 cerned with egg-colour. The character is a difficult one to classify. 

 Between the obviously broody bird that will sit regularly each year and 

 the equally obviously non-broody that never shows the least inclination 

 to sit, there are many grades, as indeed is well known. In the earlier 

 part of our experiments we kept the birds during their pullet year, and 

 classified them as non-broody if they showed no tendency to sit during 

 that period. After their first year we got rid of all the birds tested 

 through lack of space. Only after several years did we realise that a 

 bird might show no inclination to sit during her pullet year, and yet 

 might become a reliable broody the following season. We have also 



