LESSON XVI. BLOOD VESSELS. CIRCULATION. 



A. MINOR ARTERIAL SCHEME. 



This consists of an india-rubber bag, or enema syringe, 

 connected by a tube to a vessel of water and furnished 

 with two valves, one on each side of the bag and opening 

 in the same direction, so that when it is alternately com- 

 pressed and released by hand, water is drawn from the 

 vessel and delivered into tubes beyond the bag. The 

 tubes consist of a piece of glass tubing about 5 or 6 feet 

 long and a piece of rubber tubing of similar length and 

 bore and are connected to the syringe by means of a 

 three-way tube. 



There are clamps upon the long india-rubber tube 

 close to its junction with the three-way tube and upon 

 the small piece of india-rubber which connects the three- 

 way tube with the glass tube, so that the flow r of water 

 may be through either the glass or the india-rubber tube. 



A small piece of india-rubber tubing is also placed on 

 the end of the glass tube, into which a tube finely drawn 

 out can be inserted. 



1. Clamp the india-rubber tube at its proximal end 

 close to the pump, and leave the glass tube open so 

 that all the water flows through the latter. Work the 

 pump with a uniform force at about 30 to 40 strokes a 

 minute. To ensure regularity, the strokes had better be 

 timed with a metronome. The water will flow from the 

 open mouth of the glass tube in jerks, corresponding to 

 the strokes of the pump. At each stroke as much will 

 issue from the distal end as enters at the proximal end. 



