POLYSPHYGMOGRAMS. 97 



gram at which they are heard. The second (sharp) sound can be 

 heard best over the sternal end of the second rib on the right side. 



.Influence of Respiratory Movements on the Various Pulse 

 Tracings. Apply the respiratory tube to the thorax and connect 

 with a recording tambour. Also arrange to take a tracing of one 

 or the other of the pulses, or of the heart beat. Record simultaneous 

 tracings of the respiratory movements and of the pulse. Note the 

 effect of inspiration and expiration respectively on the pulse curves. 



How do you explain the effects? 



TESTING CARDIAC EFFICIENCY. 



Experiment 39. Count the pulse arid the respirations and record 

 the systolic and diastolic blood pressures of a person while 

 sitting. Then have him stand up and raise a pair of dumbbells 

 from the floor to the level of the shoulders with the arms ex- 

 tended, at a rate of 30 times a minute, and continue the exercise 

 for 2 minutes. Immediately the exercise is discontinued again 

 repeat the above observations and continue doing so at intervals 

 during the recovery period, until all the observed values have 

 returned to normal levels. It will be necessary to repeat the 

 muscular exercise several times, in order to obtain a sufficient 

 number of observations from which to obtain a complete 

 picture of the after effects. It is most important that this be 

 done carefully since it has been *found that by such methods 

 the functional capacity of the heart can best be guaged (cf. 

 Cotton, Rapport, and Lewis, Heart, 6, 269). 



Besides obtaining the data indicated above also make 

 careful observations on the following: (a) The precise moment 

 at the start of exercise at which the breathing and pulse rate 

 became changed, (b) The length of the period following exer- 

 cise during which the pulse rate and blood pressure remain 

 changed, (c) The con tour of the arterial pulse curve before and 

 after the exercise. To obtain this tracing the Dudgeon sphymo- 

 graph may be used. Note particularly whether a dicrotic wave 

 appears, (d) : The tension of CO 2 in the alveolar air. The 

 samples must be collected during and as early after the exercise 

 as possible. (Since only two or three pieces of apparatus are 

 available for these analyses the various groups must arrange 

 their experiments so that this observation can be made by all.) 

 x This observation is to be made only after Experiment has been performed. 



