ix PRACTICAL DIRECTIONS 153 



chamber, which communicates on the one hand with the 

 pharynx through the glottis, and on the other with both 

 lungs. Observe also the posterior horns of the hyoid which 

 embrace the glottis, and then separate them 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 

 larvngeal muscles in connection with the laryngo-tracheal 

 chamber : remove these, and pin the respiratory organs 

 clown under water, dorsal surface of the lungs 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 

 Rhabdonema ni^rovenosum belonging to the group of 

 Xematode worms. Note : 



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

 surrounding 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 peri- 

 toneum, 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 (or Bowman's) capsules and their 

 glomeruli. 



3. Blood-capillaries and vessels. 



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

 Part II, p. 601). 



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). 



