BRANCH CHORDATA: CLASS REPTILIA 305 



tonal. Distinguish the oesophagus, stomach, intestine, 

 rectum and the anus. 



In the region of the lung is an elongated dark-red 

 glandular mass, the liver. The secretion from the liver 

 passes down through the long Jiepatic duct to the oval- 

 shaped green gall-bladder and into the intestine. 



TECHNICAL NOTE. The bile-duct may he injected through the 

 jail-bladder with some colored injecting mass. 



Note that the duct running off from the gall-bladder to 

 the intestine passes through a pink glandular organ, the 

 Pancreas. At the anterior end of the pancreas is a dark- 

 red nodular structure, the spleen. The alimentary canal, 

 the liver and the spleen are all suspended from the dorsal 

 wall of the body-cavity by a delicate sheet of tissue. 

 What is this ? This condition we have also noted in the 

 toad and fish. 



Toward the posterior end of the bod^cavity. are two 

 long, dark-red glands, the kidneys, which are the j*in- 

 :ip:il excretory organs of the body. Through a long, 

 slender tube (the ureter} each of the kidneys passes off its 

 wastes. Where do the ureters open ? 



Anterior to the kidneys are the reproductive organs. 

 The eggs, produced by the female snake, after being 

 fertilized, pass backward through the egg-tubes. During 

 the breeding season these tubes are much distended. 

 This is due to the presence of the developing eggs, for 

 the young snakes are hatched in the egg-tubes. 



A successful injection as directed in the first technical 

 note will have filled both arterial and venous systems. 

 How does the general shape of the snake's heart compare 

 with that of the toad ? The heart consists of two ven- 

 tricles, incompletely separated, and two auricles. In the 

 snake the conus arteriosus is very much shortened and is 

 not visible. Note two large vessels arising from the 



