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 ^ to explain how some of the records 

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

 Mendelian interpretation outlined above, may be accomited 

 for. Most of these are cases of mistaken identification of 

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

 cultural College, Glasnevin, 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 tliis bull we had to look at what 

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

 The MendeHan doctrine is that the characters of the body 

 of the animal in question afiord 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 oSspring which it 

 has proved it can get. 



We have so far considered the results which follow when 



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

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

 (June, 1908). 



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