150 CHAPMAN, Spring Moult of the Bobolink. Agni 
Bobolinks may change from the winter or Reedbird plumage to 
the black, buff and white dress of the breeding male without moult- 
ing. ‘The discovery 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 Gitke 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. 
