FEATHERS, PIGMENTUM, SALIVA. 1043 



posed to be of the same nature as horn, but M. Scherer finds the 

 composition of the former to be different, and to have conside- 

 rable analogy to the second substance derived from hair and 

 horny bodies, as appears by the following analysis : 



Quills. By calculation. 

 Carbon . . 52.427 52.457 



Hydrogen . 7.213 6.958 



Nitrogen . . 17.893 17.719 



Oxygen . . 22.467 22.866 



100.000 100.000 



The composition is calculated, in the second column, from the 

 formula C 48 H 39 N 7 O I6 . By which feathers are represented as 

 having 1 atom of oxygen less in their composition than horn. 



Piymentum nigrum of the eye. This matter, carefully re- 

 moved by M. Scherer from the choroid by means of a hair 

 pencil, in distilled water, was strained with the water through 

 linen, to separate portions of membrane ; the liquid with the 

 black matter in suspension was then evaporated to dryness, and 

 the residue boiled in alcohol and ether to purify it. It contains 

 considerably more carbon than any of the preceding substances, 

 as appears by the following analysis : 



I'igmentum nigrum. 



Carbon .... 58.672 



Hydrogen . . . 5.962 



Nitrogen . . . 13.768 



Oxygen .... 21.598 



100.000 



SECTION IV. 



SECRETED FLUIDS SUBSERVIENT TO DIGESTION. 



Saliva. This liquid, which is secreted by the salivary glands, 

 contains mucus and very small transparent globules, visible 

 under microscope. It leaves, when evaporated, about 1 per 

 cent of solid matter, consisting of mucus, several salts of pot- 



2 Y Y 2 



