HABITS AND COLORATION OF THE STARLING. 287 
many years; but the first discussion by an English-speaking 
ornithologist is that by Mr. J. Amory Jefferies in the ‘ Bulletin’ 
of the Nuttall Ornithological Club (vol. vii. 1882, pp. 123-135). 
In 1895 B. Walter discussed the interference colours of feathers 
in ‘Die Oberflichen oder Schiller-Farben,” and Prof. Victor 

FEATHER FROM THE NECK OF STARLING. 
The sketches were made by transmitted light from a purple hackle taken 
from the neck of a Starling, but, so far as I have been able to discover, there 
is not even the faintest difference in microscopical appearance between a 
green and a purple feather, and this is also the case when feathers have been 
treated with caustic potash, and altered in colour. The metallic effects are 
produced only by the specially modified barbules (figs. c and p). In figs. a 
and B their distribution is indicated by the heavier shading. The line sketch 
does not give the happiest idea of the appearance of the pigmented segments. 
Viewed under the microscope these have almost the exact appearance of tiny 
panels of polished oak or teak. They are deep brown in colour, and some- 
what transparent, but the outer sheath is perfectly colourless and quite 
transparent. In the Starling these segments are by no means “over- 
lapping compartments,” and I have shown their form in figs. E (a transverse 
section) and F, which is a longitudinal section taken along the heavy black 
line on D. 
I see no reason to doubt that the brown centres to each segment are 
nothing but pigmented areas, for we get the same appearances in tracing the 
commencement of the pigmented parts on the rhachis of the feather, and the 
granular structure is confined to the dark central layer, and not, I think, to 
the outer transparent sheath. The changing tints of the Starling are thus 
due to the glossy segments of the barbules, and some readers may be inte- 
rested to know the result of a calculation as to the number of facets visible 
on the living bird: there are between 45,000,000 and 70,000,000, 
