PLUMAGES OF THE OSTRICH DUERDEN. 571 



delay the plumage stage of the particular socket. The natural order 

 according to which the various plumes appear has not yet been deter- 

 mined, but it is well established that the feathers toward both ends 

 of the wing develop in advance of those in the middle. It follows 

 from this irregular molting that, in a state of nature, the time at 

 which all the wing plumes, tail plumes, and even the coverts have 

 reached the adult plumage stage will be much later than that given 

 above. In a wild ostrich only a few of the wing plumes are growing 

 at any one time instead of the full number as in the domesticated 

 bird, where the growth is regulated artificially. 



