LUNG OF PIG. 



103 



acid, gives a perfect mould of the organ. A section gives us but a 

 single plane, and this fact must be always borne in mind. 



PRACTICAL DEMONSTRATION. 



With a very sharp razor, cut half -inch cubes from pig's lung. Se- 

 lect portions free from large bronchi, with the pleura on one side at 

 least, and harden with strong alcohol. Human lung, as fresh as pos- 

 sible, may be treated in the same manner. The epithelium of the 

 alveoli shows best in young lung. Pieces of foetal lung are easily har- 

 dened, and should be studied with reference to medico-legal work. 

 Lung must be made very hard, or thin sections cannot be cut. If the 

 ordinary 95$ alcohol does not harden sufficiently, the process may be 

 completed by transferring the tissue for twenty-four hours to absolute 

 alcohol. The celloidin infiltrating process is well adapted to this 

 structure. 



Stain human lung sections with borax-carmine, and pig's with 

 haema. and eosin. Mount in dammar. 



FIG. 75. SECTION OP LUNG OF PIG. 

 A, A. Infundibula in T. S. 



Stained with Hsema. and Eosin. x 60. 



B, B, B. Alveoli; so sectioned as to show the outline only. 



C, C, C. Alveoli; so sectioned as to present cup-shaped cavities. 



D, D, D. Alveoli; sectioned so as to divide the top (or bottom^. 



E, E. Terminal bronchi in T. S. 



