Strona, — Development of Color in Feathers. 
PLATE 8. 
Photomicrographs. 
Fig. 39. Transverse section of blue-feather germ from Passerina cyanea. X 250. 
Fig. 40. Transverse section of green-feather germ from Passerina ciris, showing 
process of pigmentation of the barbules. X 157. 
