98 Practical Zoology. 



3. Above the tongue find a small opening, the entrance to the 

 windpipe. It is called the glottis. 



4. Take six inches of glass tubing half an inch in diameter ; slip 

 over the end of this a piece of rubber tubing a foot long; this will 

 enable you to see the effect while you are inflating. Insert the 

 glass tube into the throat through the mouth ; pinch the walls of 

 the gullet closely around the blowpipe, and inflate the wide gullet 

 and stomach. 



5. For inflating the lung, a tube with a small point is better; 

 draw out a small glass tube, and connect with a rubber tube ; 

 insert the point in the glottis, and inflate. This locates the pink 

 lung, with its posterior, thin-walled extension, or air sac. How 

 far back does the air sac extend ? 



6. Trace from the glottis to the lungs the ringed windpipe, or 

 trachea. Only one lung is developed ; look for the rudiment of 

 the other. 



7. In a freshly killed snake the heart will be noticed on account 

 of its beating ; the part of it farthest from the head is the ventricle ; 

 nearer the head find two parts, the right and left auricles. These 

 two contract at the same time, just before the contraction of the 

 ventricle. The heart is in a thin sac, the pericardium ; pinch up 

 a fold of this with the forceps, and cut into it, and remove that 

 part of it covering the heart, very carefully avoiding blood tubes. 



8. Find a blood tube arising from the ventricle just between 

 the auricles, and passing forward between them, curving around 

 over the gullet to the posterior part of the body. This is the main 

 artery, or aorta ; look for its branches running to the head. 



9. Look also for an artery running to the lung, the pulmonary 

 artery. 



10. Find several veins, of a darker color than the arteries, 

 leading to the heart. 



11. Alongside the stomach is a dark red body, the liver ; a large 

 vein runs along its surface. 



12. Backof the liver is the dark bile sac; the ducts from the liver to 

 the bile sac, and from the bile sac to the intestine, are not easily seen. 



