86 STUDIES OF ANIMAL TYPES 



Circulatory organs. Cut the sac about the heart. It is 

 called the pericardium. What is the shape of the heart? 

 The heart has four chambers, like that of the mammals. 

 Snip off the posterior end of the heart and note that the 

 ventricles are distinct. The auricles are situated at the 

 anterior end of the heart. The sparrow, therefore, has a 

 double circulation. 



Note the large artery coming off from the left ventricle. 

 This is the aorta. Note that it soon gives off two branches, 

 the innominate arteries. Each of these divide into three 

 smaller arteries. The aorta runs along the back toward 

 the posterior end of the body. The right ventricle is con- 

 nected directly with the lungs by the right and left pulmonary 

 arteries. The blood is brought back to the left auricle 

 by the right and left pulmonary veins. The blood system 

 may be injected and studied in detail. For directions, see 

 Needham's " Lessons in Zoology" or Parker's "Zootomy." 



Excretory and reproductive organs. Look in the body 

 cavity, near the backbone, in the posterior part of the body 

 for the kidneys. They are three-lobed, and have two tubes, 

 the ureters, running from them to the cloaca. The kidneys 

 are partly hidden by the reproductive organs. In the male, 

 the latter consist of a pair of roundish, or oval, light-col- 

 ored testes. In the female, they consist of a large ovary, 

 sometimes containing the half -formed eggs. 



Examine the bones of the sparrow and see if they are 

 hollow. 



C. FIELD STUDY OF THE SPARROW. Very interesting 

 field studies may be carried on in connection with this 

 bird. Observe it in its natural haunts. Is it social or 

 solitary ? What does it eat ? Can it sing ? Can it hear ? 

 Can it see well ? How does it behave toward other birds ? 



