286 



VERTEBKATA 



tine near the stomach, the dark-red tongue-shaped spleen, 

 a kidney on either side of the backbone, and a pear-shaped 

 urinary bladder into which two ureters lead from the 



kidneys. The thin 

 transparent mem- 

 brane lining the 

 abdominal cavity 

 and investing the 

 organs therein is 

 the peritoneum. 

 The similar mem- 

 brane in the thorax 

 is the pleura. These 

 membranes secrete 

 a colorless serum 

 and are therefore 

 called serous mem- 

 branes, to distin- 

 guish them from 

 the mucous mem- 

 branes lining the 

 alimentary canal 

 and all other cavi- 

 ties to which the 

 air has access. 



By cutting a 

 small slit in the 

 windpipe distinguished by its numerous incomplete car- 

 tilaginous rings, and inserting and tying fast therein the 

 end of a small glass or thin tube through which to blow, 

 the lungs may be inflated as in inspiration performed by 



Fig. 323. Photograph of a lung corrosion prepared 

 by Mr. Sylvester. The trachea with all of its 

 branches was filled with melted white wax and 

 the pulmonary artery was filled with red wax, and 

 the specimen then placed in a jar of acid to eat 

 away the lung tissue, t, trachea ; a, artery to right 

 lung ; 6, left bronchus giving off air tubes to the 

 left lung. The expanded air sacs at the ends of the 

 minute branchlets are broken off. FromDavison's 



i " Mammalian Anatomy." 



