The usefulness of transmission and scanning electron microscopy for clarifying the finer details of feather morphology is exemplified. (1) The structure making a wing feather airtight is a ventral, membraneous extension of a barbule closing the gap between adjacent barbules. (2) The exposed part of the body plumage is a very open structure. This fact and the shape of barbules in transverse section suggest that water repellency is an important function of body plumage. (3) Two ways of producing colours resembling those of green vegetation by utilizing yellow carotenoids, blackish melanins, air and keratin are contrasted: a simple one in olive green feathers and a complex one in green feathers of Ptilinopus doves.