Auk 
38 CHADBOURNE on Judividual Dichromatism. van 
In short, so far as shown by the present material and methods 
of examination, “re dichromatism of Megascops asio, both in the 
species and also in the individual, is a quantitative difference in the 
distribution and relative amounts of the same morphological varieties 
of pigmented matter; and there is probably also an absolute, as well as 
a relative difference in the amount of coloring material in the various 
phases. : 
Of the chemical and other relations between the pigmented 
matter, I shall say but little now. The usual qualitative tests and 
also the methods used by Krukenberg show that ‘ zodrubin ’ 
(Krukenberg), and ‘ zodmelanin’ were present in almost all the 
feathers. No other coloring matter was detected chemically ; 
but differential staining brought out marked differences in the 
affinity of the various brown granules for certain dyes, and also 
in the color-reactions of the black and brown granules. The 
microspectroscope gave spectra agreeing with Krukenberg’s out- 
lines for ‘ zodrubin.’ 
That the pigmented matter represents successive steps in a 
process of retrograde or destructive metamorphosis, seems not 
unlikely. The subject offers an attractive field for speculation, 
but one upon which we will not enter at present. 
In conclusion, my two pets have, I think, fully proved (1) chat 
a change from the gray to the red phase of plumage did, in this case, 
actually take place in the same Screech Owl (M. asio); (2) that the 
change in question was not accompanied by increased feather-loss or 
new feather-growth (2. ¢., no ‘ moulting’ occurred); (3) that, so far 
as known the double phase was in no way due to age, sex or season 
(4) and that almost beyond question it was an instance of true * indt- 
vidual dichromatism.’ 
EXPLANATION OF PLATE. 
Figure 1. Feather from skin of ‘dichromatic’ female Megascops asto 
(coll. A. P. C. No. 4396), showing the colors and parts illustrated in the 
following figures. Slightly enlarged. Drawn and colored from nature 
by W. H. Kaula. : 
Figure 2, Barb from white portion of feather near B fig. 1. (Zeiss 
4mm. apochromat. obj. and No. 4 comp. ocular. Mounted dry.) 
Figure 3. Transverse section through barb from near D fig. 1. Shows 
distribution of pigmented matter in the deep and superficial cells. (Zeiss. 
apochromat. obj. and No. 4 comp. oc.—Celloidin and balsam.) 
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