66 ARE THE EFFECTS OF USE INHERITED ? 



(since the pigeons have increased in average size) 

 he compares it with the length of the breast- 

 bone in the rock-pigeon. 1 By this method if a 

 pigeon had doubled in dimensions while its 

 breast-bone remained unaltered, the reduction 

 would be put down as 100 per cent, whereas 

 obviously the true reduction would be one-half, 

 or 50 per cent, of what the bone should be. 

 Avoiding this error and a minor fallacy besides, 

 a sound estimate reduces the supposed reduction 

 of 13 or 14 per cent, to one of 117 per cent, which 

 is still of course a considerable diminution. 



Part of this reduction must be due to the direct 

 effect of disuse during the lifetime of the indi- 

 vidual. Another and perhaps very consider- 

 able part of the relative change must be attri- 

 buted to the lengthening of the neck or body by 



1 Variation of Animals and Plants tinder Domestication, i. 184. 

 I suspect that Darwin was in poor health when he wrote this page. 

 He nods at least four times in it. Twice he speaks of "twelve" 

 breeds where he obviously should have said eleven. 



