192 PRACTICAL HISTOLOGY [XXIV 



the necks. Slip over the end of the cannula a piece of the 

 rectum of a frog, and tie it round each neck. Open widely the 

 mouth of frog (brain destroyed, and curarised), put the cannula 

 into the glottis, slightly inflate the lungs by pinching the tubing 

 attached to the cannula, insert into the tubing a glass rod which 

 fits it. The degree of distension of the lung can then be varied 

 at will by pushing the rod in and out. The lung should not be 

 much distended. A special stand is desirable. The lung is less 

 liable to collapse in the toad than in the frog. 



Sections of amphibian lung. The septa in the frog's lung 

 enlarge at the ends, which contain a rather large blood vessel 

 and some muscular fibres ; the enlarged end is covered with 

 ciliated epithelium containing some mucous cells (respiratory 

 epithelium). Similar epithelium occurs in the lung of the newt 

 over some of the large blood vessels. 



