86 D WIGHT 



head and chin with stray ones here and there on the other 

 feather tracts. The process of moult begins at the usual points 

 and is then checked, producing the mottling of different colored 

 feathers so obvious in species with contrasting plumages. When- 

 ever a complete moult occurs either in young or old, left-over 

 feathers are the exception probably because functional activity is 

 called into full force, but when a partial moult takes place, as it 

 does in many species prior to the breeding season, parts only of 

 the feather tracts are renewed, and left-over feathers abound. 

 They are valuable landmarks, and more will be said of them 

 later for they are the chief prop of the theory of " color change 

 without moult." 



Whenever a complete moult is about to take place the first 

 tract to show activity is usually the alar, and the fall of the inner- 

 most or proximal primary is the starting signal closely followed 

 by the feathers of the breast on either side at a point pos- 

 terior to the forking of the ventral tract into its lateral branches. 

 Very shortly, new feathers appear among the interscapularies, 

 the scapularies and the greater wing coverts, and usually a little 

 later the feathers of the forehead, occiput, throat, lesser wing 

 coverts and tail coverts begin to be renewed. The moult of 

 each tract is traced elsewhere so it will suffice to say here that 

 as a' rule the moult of the wings is completed before that of the 

 body and that there are some pretty definite spots on each where 

 the last evidences are to be found. The latest feathers of the 

 alar tract are the inner secondaries (excluding the tertiaries 

 which are earlier), the under surface of the wing and the humeral 

 surfaces. On the head the latest feathers of the new dress are 

 regularly found in the postauricular region, on the nape and at 

 the nostrils ; on the back at the expansion of the dorsal tract, and 

 at the anterior extremity of the humeral tracts ; and on the ven- 

 tral tract at the chin, at the lateral forking, at the wide part of 

 the lateral branches and at the sides of the unfeathered central 

 portion of the abdomen. 



The down feathers that clothe the so-called featherless spaces 

 (apterid) keep pace with the contour feathers adjacent, but usually 

 are later. Other modified feathers, such as filoplumes, semi- 



