THE BLOOD AND ITS CIRCULATION 



■.m 



oxidized to release energy, and is stored for that purpose. The sugar 

 that becomes glycogen is carried to the liver directly from the walls of 

 the stomach and intostino, where it has been absorbed from the food 

 there' contained. From lli(< liver, blood pass(>s directly to the right 

 auricle. The portal circulation, as it is called, is the only part of the 

 circidation where the blood passes through two sets of capillaries. 



Problem XLIX. d nhidy of the circulation of the Hood 

 {.Laboratory Manual, Proh. .I'Z/A'.) 



Circulation in the Web of a Frog's Foot. — If the web of the foot 

 of a h^e frog or the tail of a tadpole is examined under the com- 

 pound microscope, a network of blood vessels will be seen. In 

 some of these the corpuscles are moving rapidly and in spurts; these^ 

 are arteries. The arteries lead into smaller vessels hardly greater 

 in diameter than the width of a single corpuscle. This network o\ 

 capillaries may be followed into larger veins in which the blood 

 moves regularly. This illustrates the condition in any tissue of 



Capillary circulation in the web of a frog's foot, as seen under the compound 

 microscope. «, b, small veins; c, pigment cells in the skin; d, ciipillnric-s in 

 which the oval corpuscles are seen to follow one another in single series. 



