100 



LABORATORY GUIDE IN PPIYSIOLOGY. 



bore the cork and pass the larger end of the tracing lever 

 through it. Fix the cork board to a ring of the support 

 with copper wire; fix the sheet lead to one end of upper 

 surface of the cork board with copper wire and pass a 

 needle through the limbs of the lead bearings and the 

 lever-cork in such a way as to bring the lever over the 

 middle of the board. The completed apparatus will 

 have the relations indicated in the accompanying cut. 

 Observations. 



(1) If the finger be held upon this elastic tube while 

 the bulb is being rhythmatically squeezed, a series 

 of impulses or pulsations will be frit by the finger 



FIG. 16. 



Place one finger upon the elastic tube near the 

 bulb, and another three or four feet from the bulb. 

 Let the bulb be pumped with sudden, but infre- 

 quent contractions. May one note a difference in 

 the time of pulsation felt by the two fingers ? If so, 

 which is felt first ? Why? What is the cause of 

 the pulsation ? 



(2) To get a tracing of this pulse, pass the rubber 

 _tube across the cork board under the tracing lever 

 ; adjust to kymograph and take trac- 

 ing. "''VW^the character of the bulb contractions 



