ix PRACTICAL. DIRECTIONS 153 



from the laryngo-tracheal chamber, so as to remove the latter, together 

 with the lungs, from the body. 



Then dissect off what remains of the mucous membrane of the pharynx 

 around the glottis, and notice the small laryngeal muscles in connection 

 with the laryngo-tracheal chamber : remove these, and pin the 

 respiratory organs down under water, ventral surface uppermost, by 

 means of a pin through each lung. Cut away the ventral wall of one 

 lung, so as to expose the cavity and its connection with the laryngo- 

 tracheal chamber. (You will very probably find some parasites in the 

 lungs small worms called Ascaris nigrovenosa, belonging to the group 

 of Nematode worms.) Note : 



1. The two arytenoid cartilages , and a ring-shaped cartilage sur- 

 rounding the base of the lungs. 



2. The network of ridges on the inner surface of the lungs. Examine 

 with a lens. Sketch. 



3. The vocal cords. Observe these first in their natural position, 

 and then with the scissors cut through the laryngo-tracheal chamber 

 along the line of the glottis so as to divide it into right and left halves 

 and thus expose the vocal cords from their surface. Sketch. 



The Kidneys, a Examine these organs in situ (Figs. 3, 4, and 7) 

 and note : 



1. Their form and position, and the relations of the peritoneum, 

 which covers them on the ventral side only, (See Fig. 5.) 



2. The ureters (their openings into the cloaca may be seen at a later 

 stage). 



3. The yellowish adrenals. 

 Sketch. 



b. Examine under the microscope a transverse section of the kidney, 

 prepared as directed on p. 136, and make out (Fig. 46) : 



1 . The urinary tubules , cut through in various planes. 



2. The Malpighian caps^des and their glomerttli. 



3. Blood-capillaries and vessels. 



4. The nephrostomes (p. 98, Figs. 23, 46 and 47, and see Part II). 

 Sketch a portion under the high power. Compare with a section of 



kidney in which the blood-vessels have been injected with coloured 

 gelatine (p. 101). 



