STRONG: DEVELOPMENT OF COLOR IN DEFINITIVE FEATHER. 173 
out molt in Passerina cyanea, described a process of rearrangement of 
melanin granules as follows: “The rhachis appeared, centrally, to be 
cellular in construction with an enveloping sheath thickly supplied with 
the black pigment matter, the granules arranged in an order suggestive 
of a streaming movement towards the tip of the feather. The stream- 
ing movement of the color granules is now especially prominent in an 
actively changing feather, and it readily appears that the rhachis gives 
up a part of its matter to the barbs, which in turn supply it to the 
barbules. A positive change of pigment is manifested macroscopically, 
for a fall feather held to the light or crushed remains yellowish in its 
yellow-colored parts, while a spring feather, appearing entirely blue, so 
treated, shows darkly, due to the addition of black pigment.” 
This idea of a streaming movement was probably suggested by the 
regular longitudinal arrangement of pigment rods in the cortex. 
An anomalous case is that of the pigment turacin which was described 
by both Church and Krukenberg as leaving the feather when the latter 
is placed in water. Krukenberg mentioned a regeneration following the 
drying of the feather. 
Fatio (66) attempted to prove that pigment may dissolve and spread 
in the feather. He placed a feather so that the proximal portion of the 
calamus was immersed in a carmine solution and observed an ascent of 
the latter in the feather structure as far as the first few barbs. He also 
noticed that when a feather is immersed in ether, the latter may pene- 
trate to the medulla of the barbs. 
Chadbourne (’97) argues for a so-called vital connection of the feather 
with the organism, ‘The mature feather (?. e., one which has reached 
full functional development) is far from being ‘dead and dry,’ a for- 
eign body no longer connected with the vital processes of the rest of the 
organism, as has sometimes been asserted ; for during ?zts life it receives 
a constantly renewed supply of fluid from the parts around it. In strong 
contrast to this is the really dead feather, in which the fluid matter is 
deficient, as, for example, the majority of cast-off feathers. Some of the 
evidence in support of these facts may be of vital interest :— (a) The 
fatty or oil-like droplets on the surface of the feather can be shown by 
micro-chemical tests (staining, etc.) to be some of them identical with 
the oil from the so-called ‘oil-gland;’ while others are totally unlike: 
that secretion; and these latter are alone found extruding from the 
pores on the surface of the rami, radii, and shaft. The pores, some with 
drops of varying size issuing from them, show best at the distal ends of 
the segments of the downy rays. (b) In the living bird the imported 
