R Staples-Browne 



135 



Experiments on Colour. 



i 



White rump x White rump 

 Blue rump x Blue rump 

 White rump x Blue rump 



Experiments on Colour of Rump \ 



47 5-25 W, rump, 175 B. rump 5 W. rump, 2 B. rump 



49, 70 

 72 



All blue rump 

 All white rump 



12 blue rump 

 2 white nmip 



is to say, that blue is a dilute form of black, and silver a dilute form of 

 dun. Messrs Bonhote and Smalley, however, take the contrary view, 

 regarding silver as dilute blue. As there is no other colour on which 

 the two middle terms of the series can be tested (as they can for 

 example in mice), it is not possible absolutely to distinguish between 

 these two alternatives. In appearance some silvers may confidently be 

 said to contain no black (e.g. Silver Rock), but in others (e.g. Silver Owl 

 and Dragoon) the colour of the wing bars hardly differs at all from that 

 of blues, and probably contains true black pigment. Unfortunately 

 microscopical tests, though extensively tried, have not hitherto provided 

 any satisfactory criterion between the various pigments, and do not add 

 much to what can be seen on ordinary inspection. 



^ In these experiments silvers are not included, as it is impossible to be certain whether 

 the rump is coloured or not. 



Joom. of Gen. u 10 



