86 Kidney. 



LUNG 



May be hardened in either chromic acid and spirit, 

 or Muller's fluid, but to harden it well the fluid must 

 be injected into the lung through the trachea. This is 

 very easily done : the lung having been removed with 

 a portion of the trachea attached, an ordinary brass 

 syringe with ivory nozzle is filled with the hardening 

 fluid, the nozzle inserted in the trachea, and the lungs 

 gently distended with the fluid ; when sufficiently full, 

 the trachea is tied and a weight attached. The lungs 

 are then placed in a tall vessel containing the harden- 

 ing fluid, which is changed as often as necessary. 



To SHOW THE EPITHELIUM OF THE ALVEOLI 



Inject through the trachea a f per cent, solution of 

 nitrate of silver, and then harden the lung by the spirit 

 process (page 13), and make horizontal sections, these 

 must be rather thick to get a correct idea of the epithe- 

 lium as lining a cavity. These specimens will show the 

 stomata between the epithelial cells. 



Lung is best stained with logwood. Sections should 

 be made through a bronchus and the small masses of 

 ganglionic cells examined, these same sections may also 

 be double or treble stained to differentiate the glands 

 of the bronchi. 



KIDNEY. 



This organ is very well hardened in chromic acid 

 mixture. 



Remove the kidneys from a freshly killed animal, 



