! LA BORA TOR Y G UWE IN PH YS1OL OGY. 



In what intercostal space is it located ? How far to 

 the left of the median line of the sternum? 



(2) Take several cardiograms from the same individual, 

 being careful so to adjust the apparatus as to gain the 

 maximum excursion of the lever. What features have 

 all of these tracings in common ? What features seem 

 to be accidental and nonessential? What are the causes 

 of the essential features? What are the sources of the 

 nonessential features? 



(3) Take cardiograms of several individuals. Do all of 

 them possess the features *which seemed essential in 

 the first series, taken from one individual ? If not, how 

 would you account for the difference? 



(4) With a stethoscope, whose construction you have 

 carefully described in your notes, listen to the heart- 

 sounds while the cardiograph is tracing the record of 

 the heart-movements. Note that two sounds are audi- 

 bh: and that there is a noticeable pause following the 

 shorter, sharper sound; let us call the sound which 

 succeeds the pause the first sound. 



(5) With what part of the cardiogram does the first 

 sound seem to correspond? With what part of the 

 cardiogram does the second sound seem to correspond? 

 Give reasons for this correspondence. 



(6) As far as the data will admit, enumerate causes for 

 the first sound; for the second sound; for the essen- 

 tial features of the cardiogram. 



