OUR BODIES AND HOW WE LIVE 



It is collected into veins which unite into a single trunk, 

 called the portal vein, which enters the liver. 



The blood, now mingling with that brought to the liver 

 by the hepatic artery, is carried by small veins which at 

 length unite into a large trunk, the hepatic vein. This vein 

 pours the blood into the inferior vena cava, which carries 

 it to the right auricle (Fig. 74). 



This loop, as we may call it, on the systemic circulation 

 is often called the portal circulation. 



Experiment 44. To show the circulation in the web of a frog's 

 foot. 1 To show the circulation in a frog's foot it is necessary to 

 hold the frog in place. Take a piece of soft wood about six inches 



long and three wide. At about 

 two inches from one end cut a 

 hole half an inch in diameter and 

 cover it with a glass slide, which 

 should be let into the wood, level 

 with the surface. Then wrap the 

 frog in a damp cheese cloth, leaving 

 one foot exposed. Next, fasten 

 a piece of thread to each of the 



1 The student may find it easier to 

 manage a tadpole than a frog. The 

 following experiment showing the cir- 

 culation of the blood in the tail of 

 a tadpole is taken from Peabody's 

 Laboratory Exercises in Anatomy and 

 Physiology, p. 56. 



Cut a hole a half inch square near the end of a piece of thin board three 

 inches long and one inch w r ide ; glue a thin cover glass over the hole. 

 Cover the rest of the piece of wood with absorbent cotton soaked in water. 

 Lay a live tadpole on the cotton, placing the tip of the tail on the cover 

 glass. Lay a cover glass on top of the tail, and fasten cheese cloth over 

 the animal to keep it in place. Keep a plentiful supply of moisture about 

 the animal by allowing the end of the strip of cloth to dip into a dish of 

 water. Examine the tip of the tail with a compound microscope magni- 

 fying about seventy-five diameters. 



FIG. 94. 



Showing how the circulation of blood 

 in the web of a frog's foot looks as 

 seen under the microscope. 



