3 8 Chadbourne on Individual Dichromatism. \^t^ 



In short, so far as shown by the present material and methods 

 of examination, the dichromatism of Megascops asio, both in the 

 species and also in the individual, is a quantitative difference in the 

 distribution and relative atnounts of the. same morphological varieties 

 of pigmented matter; and there is probably also an absolute^ as 7vell as 

 a relative difference in the a7nount 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 ' zoorubin ' 

 (Krukenberg), and ' zoomelanin ' 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 ' zoorubin.' 



That the pigmented matter represents successive steps in a 

 process of retrograde or destructive metamorphosis, seems not 

 unlikely. The subject offers an attractive lield for speculation, 

 but one upon which we will not enter at present. 



In conclusion, my two pets have, I think, fully proved (i) that 

 a change from the gray to the red phase of plumage did, in this case, 

 actually take place in the sa?ne Screech Owl {M. asio) ; (2) that the 

 change in question was not accompanied by i?icreased feather-loss or 

 new feather-grotvth (/. e., no ' fnoulting ' occurred) ; (3) that, so far 

 as known the double phase was in no ivay due to age, sex or seaso?i ,' 

 (4) and that almost beyond question it was an instance of true ' indi 

 7ndual dichromatism . ' 



Explanation cJf Plate. 



Figure i. Feather from skin of 'dichromatic' female Megascops asio 

 (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. i. (Zeiss 

 4mm. apochromat. obj. and No. 4 comp. ocular. Mounted dry.) 



Figure 3. Transverse section through barb from near D fig. i. Shows 

 distribution of pigmented matter in the deep and superficial cells. (Zeiss 

 apochromat. obj. and No. 4 comp. oc. — Celloidin and balsam.) 



