300 



DOMESTIC DUCKS. 



GnAP. VIII. 



In these domesticated birds, the considerably lessened weight of 

 the bones of the wing (i. e. on an average, twenty-five per cent, of 

 their proper proportional weight), as well as their slightly lessened 

 length, relatively to the leg-bones, might follow, not from any 

 actual decrease in the wing-bones, but from the increased weight 

 and length of the bones of the legs. The first of the two tables on 

 the next page shows that the leg-bones relatively to the weight of 

 the entire skeleton have really increased in weight ; but the second 

 table shows that according to the same standard the wing-bones 

 have also really decreased in weight; so that the relative dis- 

 proportion shown in the foregoing tables between the wing and leg- 

 bones, in comimrison with those of the wild duck, is partly due to 

 the increase in weight and length of the leg-bones, and partly to 

 the decrease in weight and length of the wing-bones. 



With respect to the two following tables, I may first state that I 

 tested them by taking another skeleton of a wild duck and of a 

 common domestic duck, and by comparing the weight of all the 

 bones of the leg with all those of the wings, and the result was the 

 same. In the first of these tables we see that the leg-bones in each 

 case have increased in actual weight. It might have been expected 

 tliat, with the increased or decreased weight of the entire skeleton, 

 the leg-bones would have become proportionally heavier or lighter; 

 but their greater weight in all the breeds relatively to the other 

 bones can be accounted for only by these domestic birds having 

 used their legs in walking and standing much more than the wild, 

 for they never fly, and the more artificial breeds rarely swim. In 

 the second table we see, with the exception of one case, a plain 

 reduction in the weight of the bones of the wing, and this no doubt 

 has resulted from their lessened use. The one exceptional case, 



