THE ENGLISH SPARROW. 121 



between the ribs. How do they compare in spongy texture with 

 the lungs of the domestic mammals we use for food ? Are they 

 relatively large or small ? How do you account for the marked 

 swelling of the whole body when you inflated the trachea ? 



i) Each lung is connected with the trachea by a short branch of the 

 latter called a bronchus. At the junction of the bronchi with 

 the trachea is the syrinx or voice-box containing the so-called 

 vocal cords. Where is the voice-box of mammals located ? 



j) Back of the lungs, and fitting closely into the hollows of the pelvis, 

 are the dark colored kidneys. How many lobes compose each 

 kidney ? Try to find a slender duct ureter connecting each 

 kidney with the cloaca. 



k) In front of and partly overlying the kidneys are the reproductive 

 organs two white oval testes in the male and a single ovary in 

 the female. These organs will vary in size according to the season, 

 though the ovary will usually show eggs, or ova, in different 

 stages of development. The right ovary is commonly wanting 

 entirely in birds, as is also the tube oviduct which would con- 

 nect it with the cloaca. Can you find a vestige of this tube at- 

 tached to the right side of the cloaca ? Trace the left oviduct. 

 Trace the tube vas deferens connecting each testicle of the 

 male with the cloaca. 



Exercise 6. Make a sketch properly locating in the body outline all of the 

 internal organs except the "various divisions of the food tube. 



Exercise 7. Make a diagram of the digestive tract exterior to the body 

 outline. 



Split the gizzard and examine its interior, noting the contents, the 

 thick, muscular walls, and the hard, rough lining. Separate the lining 

 from the muscular walls. Account for the gravel mixed with the food. 



Remove the heart and examine its chambers and the stubs of veins 

 and arteries connected with it. Make two or three cross sections. 

 Why are the walls of the left ventricle thicker than those of the right ? 



Carefully remove, with scissors, the roof of the skull and examine 

 the brain. The large division in front is the cerebrum. Note the 



