An Introduction to a Biology 



tween the two cases that of the Andalusian fowl and that 

 of the shorthorn cattle. There is never, so far as my obser- 

 vations go, any difficulty in distinguishing a black bird from 

 a blue one ; they do not merge into one another by transi- 

 tional stages ; but it is sometimes difficult to say whether 

 a beast is a red or a roan. There is a curious case referred 

 to by Prof. James Wilson 1 to explain how some of the records 

 in the Herd-Book, which are not in accordance with the 

 Mendelian interpretation outlined above, may be accounted 

 for. Most of these are cases of mistaken identification of 

 colour. " A bull now standing (1908) at the Albert Agri- 

 cultural College, Grlasnevin, was registered in the Herd-Book 

 by his breeder, who is the most distinguished breeder in 

 England, as being red. This bull's sire was white ; his dam 

 was red ; and he ought therefore to be roan. He has bred 

 several white calves from roan cows ; and on this ground 

 also he ought to be roan. On close inspection he is a roan, 

 but such a roan as might easily be mistaken for a red." I 

 mention this case because it affords a striking illustration 

 of the change which has been brought about by Mendel's 

 work. The old pre-Mendelian system was to estimate how 

 an animal would breed by looking at it (and its ancestors) ; 

 if we were breeding for colour we should look at the colour 

 of the animal in question in order to foretell what its off- 

 spring would be. But Mendel has completely turned the 

 tables ; and in the case of this bull we had to look at what 

 his offspring had been in order to tell what colour he was ! 

 The Mendelian doctrine is that the characters of the body 

 of the animal in question afford a very meagre clue to the 

 value of that animal as a breeder ; the proof of the animal 

 is in its breeding that is to say, in the offspring which it 

 has proved it can get. 



We have so far considered the results which follow when 



1 " Mendelian Characters among Shorthorn Cattle." " Scientific Pro- 

 ceedings of the Koyal Dublin Society," Vol. 11. (N.S.), No. 28, p. 322. 

 (June, 1908 )*.. 



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