THE SNAKE. 101 



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 5 

 a large vein runs along its surface. 



12. Back of the liver is the dark bile-sac, and near this 

 the spherical red spleen. 



13. Clear away any masses of fat that may hide organs in 

 the posterior part of the body, and again inflate the 

 stomach and lung for a more perfect view of these 

 organs. 



14. Trace the intestine from the hinder end of the 

 stomach to the opening, the anus, at its posterior end. 



15. In the hinder part of the body-cavity may be found 

 the reproductive organs, ovaries in the female, testes 

 in the male. These both have long tubes, extending 

 backward to convey their contents to the posterior, 

 dilated portion, the cloaca, of the intestine. 



16. Into the cloaca also open the ducts of the kidneys, 

 two reddish, elongated structures. 



17. Count the ribs of one side. 



18. Draw the points of the forceps quickly along the 

 muscles over the ribs; note the contraction of the 

 muscles that follows ; such contraction of the muscles 

 is wholly involuntary (as the brain now has no con- 

 nection with the body), and is called reflex action of 

 the spinal cord. It is the same kind of action as that 

 seen in the case of a chicken with its head cut off. 



Use " Jordan's Manual of the Vertebrates" for finding 

 the names of snakes. 



