Chap. V. ON THE EFFECTS OF DISUSE. 183 



feet too short, on an average by a little above the tenth of an inch 

 (viz. '107) ; and five specimeus have their feet on an average a very- 

 little too long, namely, by -07 of an inch. But some of these latter 

 cases can be explained ; for instance, with Pouters the legs and feet 

 are selected for length, and thus any natural tendency to a dimi- 

 nution in the length of the feet will have been counteracted. In 

 the Swallow and Barb, when the calculation was made on any 

 standard of comparison besides the one used (viz. length of body 

 from base of beak to oil-gland), the feet were found to be too small. 



In the second table we have eight birds, with their beaks much 

 longer than in the rock-pigeon, both actually and proportionally with 

 the size of body, and their feet are in an equally marked manner 

 longer, namely, in proportion, on an average by -29 of an inch. I 

 should here state that in Table I. there are a few partial exceptions to 

 the beak being proportionally shorter than in the rock- pigeon : thus 

 the beak of the English Frill-back is just perceptibly longer, and that 

 of the Bussorah Carrier of the same length or slightly longer, than in 

 the rock-pigeon. The beaks of Spots, Swallows, and Laughers are 

 only a very little shorter, or of the same proportional length, but 

 slenderer. Nevertheless, these two tables, taken conjointly, indicate 

 pretty plainly some kind of correlation between the length of the 

 beak and the size of the feet. Breeders of cattle and horses believe 

 that there is an analogous connection between the length of the 

 limbs and head ; they assert that a race-horse with the head of a 

 dray-horse, or a grey-hound with the head of a bulldog, would be a 

 monstrous production. As fancy pigeons are generally kept in 

 small aviaries, and are abundantly supphi^d with food, they must 

 walk about much less than the wild rock-pigeon ; and it may be 

 admitted as highly probable that the reduction in the size of the 

 feet in the twenty-two birds in the first table has been caused by 

 disuse, ^ and that this reduction has acted by correlation on the 

 beaks of the great majority of the birds in Table I. When, on the 

 other hand, the beak has been much elongated by the continued 

 selection of successive slight increments of length, the feet by corre- 

 lation have likewise become much elongated in comparison with 

 those of the wild rock-pigeon, notwithstanding their lessened use. 



As I had taken measui-es from the end of the middle toe to the 

 heel of the tarsus in the rock-pigeon and in the above thirty-six 

 birds, I have made calculations analogous with those above given, 

 and the result is the same. — namely, that in the short-beaked 

 breeds, with equally few exceptions as in the former case, the 

 middle toe coujointly with the tarsus has decreased in length ; 

 whereas in the long-beaked breeds it has increased in length, 

 though not quite so uniformly as in the former case, for the leg in 

 some varieties of the Runt varies much in length. 



3* In an analogous, but converse, allied groups, have larger feet. Sea 



manner, certain natural groups of Prince Bonaparte's ' Coup-d'oeil sur 



the ColurabiJa;, from being more ter- I'Order des Pigeons.' 

 iesti'ial in titir habits than other 



