88 THE ZOOLOGIST. 
In such specimens as are in a state of transition from one 
stage of plumage to another, we may, if other signs are wanting, 
easily discover, with the aid of the microscope, which feathers are 
new, for the old ones always show signs of wear. 
Fig. 16 is a green feather-branch from the breast of a male 
Trochilus rubineus. The outer colourless radii, which form the 
winter plumage, have all nearly fallen off; the point of the branch 
probably remains until the next moult. 
Amongst those birds in which plain point-casting takes place 
should be included Cuculus cupreus. Fig. 17 shows a feather 
branch from the breast of a male of this species. The radii 
points turned upon the left side have much to do with the unusual 
golden lustre of the feather. 
Fig. 18 is a branch of: the lance-shaped copper-red neck- 
feathers of the male Lophophorus impeyanus. The radii on one 
side only of the branches are metallic, for those on the other 
side lie concealed under them. A similar formation is found in 
the green throat-feathers of Paradisea apoda and in Epimachus 
regius and magnificus in their blue-green neck- and head-feathers. 
On the other hand, the velvety breast-feathers of EH. regius show 
on the coloured side a very different formation of the radii. 
Here the radii may be compared to a row of arrow-heads stuck 
into each other, and having the barbs standing upwards. 
Resemblance in the form of the radii does not show that 
Species possessing similarly formed radii are closely akin, but 
has probably an important bearing on the feather’s lustre, 
changes, &c. 
Fig. 19 is a piece of a blue feather-branch from the breast of 
Pawo cristatus. 
Fig. 20 is a piece of a brown feather-branch from the breast 
of Anas boschas in the spring. The radii are cast from the point 
of the branch, which is not drawn. In the autumn the breast- 
feathers have besides small white borders. The remaining radii 
are twisted one turn. This peculiarity I have noticed in many 
ducks. On the left side are two radii with hooks (hamuli), in 
order to fasten the radii to each other. Such are found to be 
especially numerous in the water-fowl. 
Fig. 21 represents a portion of a reddish-brown breast-feather 
of Podiceps auritus. Here the radii are twisted two turns; 
