456 On Change io Spring Plumage without a Moult. 



during that period), and as we have the proof of all inter- 

 mediate changes of the feather taking place, there seems 

 equally little reason to doubt that fig, 8 also passes into 

 fig. 9, for here we again have the transition shown. 



We know that many of the small perching- birds assume 

 their summer plumage by means of the grey edgings of the 

 feathers wearing off; I do not, however, think that this 

 takes place, in the case of the Sanderling, in the change from 

 fig. 10 to fig. 11, but that it is the colouring-matter moving 

 down the feather and obliterating the white. After this 

 change I think that the edge of the feather then wears 

 away in an appreciable degree, causing its form to be altered, 

 as seen in fig. 12. 



To sum up, so far I see no reason whatever to differ from 

 the opinions of many of our own naturalists, and I maintain 

 that Herr Gatke^s solution of the spring change of the 

 Dunlin and the Sanderling is perfectly correct as regards 

 an actual influx of pigment through the old feather, whilst 

 Mr. Frank M. Chapman^s observations on these two birds 

 in the same journal as Mr. Allen's require modification. We 

 know well that new feathers come in place of the few that 

 are cast, but that is no evidence that the whole bird undergoes 

 a moult of all except the rectrices and remiges. 



EXPLANATION OF PLATE X. 

 Method No. II. 



ScLAVONiAN Grebe, S {PodicijJes auritus). 



Neck-feathers from the front of lower part of neck, showing change 

 from winter to summer plumage. 



A fine example of the most common type of spring change. The 

 majority of the feathers are not moulted, hut change colour ; whilst those 

 feathers which are cast are replaced by new summer-plumage feathers, 

 which themselves assimilate their colour to the old feathers now in 

 process of change. 



1. Winter neck-feather before commencing to change. From a bird 



shot in January. Stromness, Orkneys. 



2. First indication of change. The rich red colour seen emanating from 



sides of the quill. April 2nd. Same locality. 

 3 & 4. Feather still undergoing its further change. April 10th. Same 

 locality. 



