THE ENGLISH SPARROW. 211 



the right side of the body. Insert a blowpipe into the 

 glottis and inflate the lung. Observe a prominent branch- 

 ing pulmonary artery running along the inner side of the 

 lung. Cut away the upper part of the pericardium and 

 trace this artery back to the heart. Through it blood is 

 conveyed from the heart into the lung for aeration. 



Observe on the inner side of the liver a prominent vein 

 coming from the posterior part of the body cavity, bring- 

 ing the blood back to the heart. Trace outward from 

 the heart the aorta (the principal artery), which arises 

 from the ventricle between the auricles, bends upward and 

 backward about the esophagus, and passes straight through 

 the body cavity posteriorly, giving off branches which 

 supply blood to all the parts. 



The lung is single, but the rudiment of its undeveloped 

 mate may be found by dissecting out the trachea. Dis- 

 sect out the lung. Inflate it through the glottis, and tie 

 the trachea with a thread to keep it inflated. Dry it, and 

 compare it in structure with the lungs of the frog and the 

 turtle. 



Compare the snake with the turtle in respect to 



1. Means of locomotion. 



2. Character of mouth parts. 



3. Character of scales. 



4. Shape of body cavity. 



5. Relative development of internal organs. 



THE ENGLISH SPARROW. 



(Passer domesticus.) 



An Interloper. This bird and its haunts are too well 

 known to need description. It was introduced into the 

 United States about 1850, and has since overspread the 

 whole country. It is the only bird to be found in many of 



