THE CIRCULATION OF THE BLOOD. 



45 



represents an injury to an artery, and a cor- 

 responding outlet in the other half represents 

 an injury to a vein. 



a. Connect the pump with the large ar- 

 tery, and slowly force the air out of the set 

 of tubes, and water, slightly colored red, into 

 the tubes. Imitate the action of the heart 

 with seventy-two slight strokes a minute. 

 Watch the circulation of the water through 

 the tubing. 



b. Hold in the hand a large artery and 

 feel and count the pulse. Feel the pulse in 

 a small artery. How do the two compare ? 

 Feel of a capillary. Is there any pulse? 4 

 Feel of a small vein and then a large vein 

 for the pulse. Where is the pulse most E 

 prominent? Where is it least felt? 



c. Remove the stop-cock at H and con- 

 tinue the action of the pump. Is the out- 

 flow continuous or intermit- 

 tent ? How does the blood flow 



from an injury in an artery ? 



d. Remove the correspond- 

 ing stop-cock in the large vein, 

 and replace the stop-cock in 

 the artery. Continue the 

 action of the pump. Is the 

 outflow continuous or inter- 

 mittent ? How does the blood 

 flow from an injury in a vein ? 



e. How does the flowing of 



halfway g\ I | I I I II 



FIG. 4. One fourth of the apparatus 

 to illustrate the circulation of the 

 blood. 1,2, an d 3 are of the 12m .111. 

 rubber tubing ; 4 is of 6 m.m. rubber 

 tubing ; 5 and 6 are of 5 m.m. rubber 

 tubing ; A and E are the 12 m.m. 

 three-way, reshaped, connecting glass 

 tubing; E is a three-way, F-shaped, 

 glass tube ; fis the 4 m.m. three-way, 

 F-shaped, glass tubing ; D is a three- 

 way, T-shaped, connecting glass tube; 

 C is the connector made from 12 m.m. 

 glass tubing, drawn down to fit the 

 rubber tubing 6 m.m. in diameter ; 

 (j is of the 4 m.m. glass tubing, which 

 is filled with pieces of fine sponge, 

 or with pieces of glass rod 2 m.m. in 

 diameter. 



