IN THE FEATHERS OP BIRDS. 



Text-figure 4. 



227 



Fig 



Fij 



Fie 



. 1. Diagrammatic drawing of a Feather, showing Stem, Branches, and Leaves. 

 . 2 a. Feather from the gorget of Humming-Bird (X20). 



2 h. Termination of single branch of same feather (X30). 



2 c. „ „ ,, of coloured body-feathers from the same 



bird (X 30). 



2 d. Termination of gorget-feather (X 130), showing the leaves and their prolon- 

 gations ip-p), which serve to keep the former regularly spaced, andthe 

 planes of their upper surface inclined at a constant angle to the axis of 

 the branch. 



2 e. Cross-section of gorget-feather, parallel to the line XX of 2 a (X20). 



2/. Cross-section, parallel to X X of 2 cZ, of single branch of the same feather 

 (X130). Note the sections of the prolongations of the leaves at p p. 



2 ff. Longitudinal section of the same, parallel to Y Y of 2 d. 



.3a. Featherfrom the wing of King Bird-of-Paradise by reflected light (X40). 



3 b. Part of a single branch of same feather (X130), showing leaves developed 



on one side of the branch only. 

 3 c. Cross-section of leaves, parallel to X X in 3 6 (X220). 



3 d. Longitudinal section of one of the leaves of same feather. 



. 4b a. Branches of blue feather from Peacock's neck by transmitted light (X30). 



4 b. The same by reflected light (X40). 



4 c. Cross-section of single branch of same (X130). 

 4 c?. Part of a single leaf of same, seen in perspective. 



