STRONG: DEVELOPMENT OF COLOR IN DEFINITIVE FEATHER. 173 



out raolt in Passerina cyanea, described a process of rearrangement of 

 melanin granules as follows: " The rhachis appeared, centrallj^, 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 (z. e., one which has reached 

 full functional development) is fir from being ' dead and dry,' a for- 

 eign body no longer connected witli the vital processes of the rest of the 

 organism, as has sometimes been asserted ; for during its 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 flicts maybe 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 witli 

 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 poi'es, 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 



