1916] Chandler: Structure of Feathers 279 
I can think of no more striking example of isotely, the attainment 
of the same end by different methods in different groups, than 
these manifold methods of producing a single color. 
2. Effect of Albinism on Structural Color Modvfications 
One of the most remarkable things about the morphology of 
feathers is the profound change of structure so frequently involved 
in the production of color effect, in spite of the surprising con- 
staney of group characters where no such color modifications occur. 
It was with extreme interest that the writer examined some of the 
feathers of an albino mallard, Anas platyrhynchos, to see whether 
the morphologic modifications involved in the production of the 
violet speculum would be lost or retained with the lack of pig- 
ment. It was found that the distal barbules of the outer vane, 
which in a normal mallard have the pennula highly modified for 
the production of color (pl. 21, fig. 28a), lacked this modification 
entirely, and were exactly similar to the normal distal barbules of 
the outer vane of feathers of this species in which there was no 
modification for color (pl. 21, fig. 28e). In other words, the con- 
stitutional factor causing the morphologic specialization of feather 
structures for the production of color is inseparably bound together 
with the factor for the accompanying pigment, and if the latter is 
absent, the feather structures present the normal type of the species 
in which there are no color modifications. 
