276 



THE METALLIC COLORS OF FEATHERS 



Strong, R. M. 



:02. The Metallic Colors of Feathers from the Neck of the Domestic Pigeon. Biol. Bull., vol. 3, nos. 1 and 

 2, pp. 85-87. 



Strong, R. M. 



:02". The Development of Color in the Definitive Feather. Bull. Mus. Comp. Zool. Harvard Coll., vol. 

 40, no. 3, pp. 147-185, pis. 1-9. 



Tyndall, J. 



'69. On the Blue Colour of the Sky, the Polarization of Skylight, and on the Polarization of Light by 

 Cloudy Matter generally. Phil. Mag., ser. 4, vol. 37, pp. 384-394. 



EXPLANATION OF PLATE XX. 



Figures 1-14 were outlined with the aid of an Abb6 camera lucida. Figures 2-10 were drawn from dissected 

 preparations mounted dry on the slide. Figures 11-14 are from preparations mounted in balsam. Figures 5-10 

 are lateral views of single barbules. All figures were made from the feather shown in Figure 1 or from a similar 

 feather. 



ABBREVIATIONS (Fios. 1-14). 



brb. Barb. 



brbc. Barbicel. 



brbc'. Vestigial barbicel. 



brbl. Barbule. 



brbl. dst. Distal barbule. 



brbl. prx. Proximal barbule. 



d'. int. Inter-cell boundary. 



d. Dorsal. 



d'. Dorsal iridescent face of barbule. 



dst. 



dstf. 



gran. pig. 



mac. pig. 



marg. 



nl'. 



prx. 



tu. 



v. 



Distal. 



Distal iridescent portion of feather. 



Pigment-granules. 



Pigment-patches. 



Recurved margin. 



Position of nucleus. 



Proximal. 



Outer transparent layer of barbule. 



Ventral. 



LATE XX. 



Fig. 1. Dorsal view of a feather from the side of the neck of a homer pigeon giving metallic colors. Only the 



darkened distal portion (dst'.} shows these colors. Xl. 



Fig. 2. Dorsal view of a barb and its barbules in the region of transition from non-metallic to metallic colors. X37. 

 Fig. 3. Dorsal view of a portion of a barb and its barbules near the proximal end of the barb, from the right side 



of the feather shown in Figure 1. XI 00. 

 Fig. 4. Dorsal view of barbules from the metallic-colored region of the barb used for Figure 3; brbc'., vestigial 



barbicels. X 100. 



Fig. 5. Distal barbule from the region shown in Figure 3. X 100. 

 Fig. 6. Distal barbule from the transitional region shown in Figure 2. X 100. 

 Fig. 7. Distal barbule from the region shown in Figure 4. XlOO. 

 Fig. 8. Proximal barbule from the region shown in Figure 3. X 100. 

 Fig. 9. Proximal barbule from the transitional region shown in Figure 2. X 100. 

 Fig. 10. Proximal barbule from the region shown in Figure 4. XlOO. 

 Fig. 11. Cross-sections of several barbules cut somewhat obliquely. Section prx 1 . represents a barbule near its 



attachment to the barb, and section dst'. a more distal portion of another barbule. X540. 

 Fig. 12. Cross-section of a barbule similar to those shown in Figure 11. X1080. 

 Fig. 13. A lateral, sectional view of a metallic-colored barbule near its middle. X540. 



