60-i 



MESSRS. J. LEWIS BONHOTE AND F. W. SMALLEY ON 



allelouiorph is therefore concentration and dilution (c and d) of 

 ^^•luch the former is dominant. 



BUie may therefore be represented as BBcc or BRed, x^here B 

 represents the bhie cokiur factor. Silver must theretoi-e be repre- 

 sented by BBdd. 



Bhies are said to ahnost always breed true, that is to say, that 

 they never throw any Silvers — this idea owes its oiigin, however, 

 to the fact that those Blues which are impure dominants {i. e. 

 containing the factor d) are of a poorer colour than the pure BJues 

 and have in consequence long been rejected by fanciers, so that a 

 race of pure dominants has thus been evolved*. Several of our 

 matings show that Blues or Grizzles that- are heterozygous as 

 regards cand d will throw Silverst. 



The following ai'e the results of our matings for these particular 

 characters, with the exception of Experiment 83, which is intro- 

 duced to show tlie reappearance of Silver from two heteiozygous 

 Blues. 



When the Gametic Formula is in italics it implies that it is not definitely/ known. Only the 

 chai-acters under immediate consideration are given in the Gametic Formula. 



* See also remarks on chequering. 



t We must, however, point out here that in Mr. Staples-Browne's experiments, 

 one or two blues, apparently heterozygous, behaved as homozygous and vice versa. 



X With regard to the numbering ot Experiments — the numbers refer to our stud 

 hook, and rather than n\imlier the experiments quoted successively in th:s paper, it 

 was thought best to have only one set of numbers so that references might at any 

 future time he easih- made without risk of confusion. 



