MASCHA ] STRUCTURE OF WING—FEATHERS 25 
III. SumMaAryY OF RESULTS 
1. In the core of the secondary quills the cells may be so arranged 
as to form several irregular, or one single regular layer. The first 
type is the more frequent. The second is met with chiefly in the 
Striges and Caprimulgi. | 
2. All secondary quills have a ventral hornridge. It varies be- 
tween a low crest (Cypselus, Columba) and a large, curved, mem- 
branous plate (Diomedea, Striges, Cygnus). 
3. The degree of concavity of the secondary quill is correlated 
to the size of the central hornridge. 
4. At the origin of the tertiary fibers from the secondary quills 
very complicated structures are met with. Here a projecting longi- 
tudinal ledge occurs from the upper side of which oblique crests 
protrude, parallel and close together like the bars of a gridiron. 
Between these crests lie the proximal portions of the tertiary fibers. 
5. The diminution in height of the secondary quills from the 
main quill outward may be gradual, constant and moderate, or in- 
terrupted by a step, as in Striges and Cygnus. 
6. The height of the secondary quills is greatest either at the 
feather base (Aquila, Diomedea) or more frequently above the mid- 
dle of the length of the feather (Cygnus, Bubo, Macropteryx). 
7. The teeth of the outer feather-vanes of the first three remiges 
of the owls are peculiarly differentiated tips of secondary quills. 
8. The hook-fibers always spring from the inner side of the sec- 
ondary quill which is turned toward the main quill and the feather- 
tip. They are transversely curved bands composed of a single row 
of cells. These cells may possess projections which are, proximally, 
dorsal lobes and ventral hooks; distally, dorsal and ventral spines. 
g. The number of hooks on each hook-fiber is 2 to 8; it is con- 
stant in the same species. 
10. Peculiarly shaped hook-fibers are found in the Striges and 
Caprimulgi. In the former they are very long and provided with 
numerous large spines; in the latter likewise they are long, but 
have no distal spines. 
11. The distance between the hook-fibers in the functional remiges 
of all classes of birds varies only between 20 and 30 p. 
12. The curved fibers spring from the outer side of the secondary 
quill which is turned away from the primary quill and toward the 
feather basis. They are transversely curved bands, like the hook- 
fibers which they resemble in many points. 
13. The dorsal, dentate projections at the bend of the curved fibers 
are an arresting apparatus. 
