84 SPECIAL PHYSIOLOGY 



IV. THE FLOW OF LIQUIDS THROUGH TUBES UNDER THE 

 INFLUENCE OF INTERMITTENT PRESSURE. 



A. The Influence of Intermittent Pressure. 



1. Appliances. A glass tube of about 6-mm. lumen and about 

 100 cm. long; a thin- walled elastic tube of about the same lumen 

 as the glass tube and about 100 cm. long; a double- valved, strong 

 rubber bulb (about 7.5 cm. long); very thick-walled rubber tubing 

 for joining up the apparatus; a 2-litre jar and a flask or water recep- 

 tacle; heavy linen thread; a wide capillary and a fine capillary or 

 a piece of glass tubing 10 cm. long for constructing the same; 500-c.c. 

 graduated cylinder; piece of 8-mm. rubber tubing about 50 cm. 

 long. 



2. Preparation. Join the large elastic tube to the entrance valve 

 of the bulb. Couple the glass tube closely to the exit valve of the 

 bulb. Make all joints as close as possible, and tie tightly with 

 thread. Draw a coarse and fine capillary tube from the 10-cm. 

 piece of glass tubing. Fill the jar with water and immerse the tube 

 from the entrance valve in the water. 



Clasp the bulb in the hand and make rhythmical contractions at 

 the rate of ten to fifteen in ten seconds. This process will, of course, 

 pump water from the jar into the flask held at the distal end of the 

 long glass tube. One person should pump the bulb and the greatest 

 care should be taken to exert the same force and use the same rate 

 in the several observations. 



3. Observations, a. Intermittent force and inelastic tubes. 



(1) Does the stream of water which is ejected from the exit tube 

 flow in a constant or in an intermittent jet? 



(2) Attach a wide capillary and repeat. What is the character 

 of the stream? Measure the discharge in ten seconds. 



(3) Attach a fine capillary and repeat. Measure the discharge in 

 ten seconds. 



b. Intermittent force and elastic tubes. 



(4) Disjoin the glass tubing from the bulb and join the 100-cm. 

 elastic tube. Work the bulb as directed above and observe the 

 character of the flow. Measure the quantity of discharge. 



(5) Join on the coarse capillary and repeat, noting the change in 

 the character of the jet and the amount of discharge. 



(6) Replace the coarse capillary with the fine capillary and repeat. 

 Sum up results and formulate conclusions. 



B. The Pulse or Impulse Wave. 



By putting the finger upon the rubber tube while the bulb is in 

 action the pulse may be felt. To trace this upon the kymograph 



