I^O Chapman, Spring Moult of the Bobolink. \ k^\\ 



Bobolinks may change from the winter or Reedbird plumage to 

 the black, buff and white dress of the breeding male without moult- 

 ing. The discover}' is of such importance and has so wide a 

 bearing upon problems connected with changes of color in the 

 plumage of birds, that, having handled a large part of the 

 material which Dr. Chadbourne has studied, it has seemed advis- 

 able to follow his paper with remarks upon several questions he 

 has therein discussed. 



Laying aside for a moment the fact that the change observed 

 occurred in a caged bird, we have here for the first time a 

 definite description of a change in the color of a bird's plumage 

 without moult with an explanation of its cause in certain 

 feathers. This change, it should be noted, is not due to repig- 

 mentation, or " influx of new pigment," which has so often 

 been spoken of as an observed fact, nor even to a chemical 

 change in the pigment, but to a redistribution in the shaft or 

 barb of the feather, of the existing pigment. Dr. Chadbourne 

 says : " Thus in the black spring specimen the granules are 

 peripheral and comparatively close together, though a smaller 

 number are also found in the deeper parts ; while in the autumn 

 the granular pigmented matter is more uniformly scattered through- 

 out." It will be observed therefore that no vascular connection 

 between the feather and the dermal papilla in which it is set is 

 claimed, nor is there any evidence to show that the feather can 

 renew itself either by repigmentation, or by a fresh growth 

 restoring a worn or ragged feather to its perfect shape, as claimed 

 by Herr Gtitke and other theorists. It is these two theories, 

 repigmentation and new growth in an old feather, that Dr. Allen 

 and others have combated as physiologically impossible, and 

 Dr. Chadbourne alone of all the advocates of color-change with- 

 out moult, has shown that this change may take place by a 

 comparatively simple process, which nevertheless accomplishes 

 remarkable results. 



In demonstrating his point Dr. Chadbourne has placed in our 

 hands a very dangerous tool. It is evident that extreme care is 

 necessary in conducting observations of the kind he has made, 

 and that satisfactory results can only be obtained through con- 

 tinued observation of the same individual. 



