PULSE DURING MENTAL AND PHYSICAL WORK. 235 



period of the registering system, as well as to the broadness of the 

 dicrotic notch. 



Fortunately the Dodge temporal-pulse recorder, in series with the 

 string galvanometer, gave sphygmograms which are peculiarly adapted 

 to the differentiation of systole and diastole. Not only is the string 

 galvanometer an aperiodic recorder, but the form of the pulse-wave is 

 such as to emphasize the beginning of systole and the dicrotic incisure. 

 Without going into the details of the construction and operation of the 

 recorder, let us recapitulate its principles. The string galvanometer is 

 affected by minute electric currents which are generated in a telephone- 

 receiver, when the little armature which rests on the artery moves 

 towards or away from the permanent magnet of the receiver. The 

 action of the armature on the field of the receiver and consequently on 

 the string of the galvanometer depends on the speed and direction of 

 its movement. If the armature is at rest or moves only slowly, as in 

 the systolic plateau, the string returns to its zero-point, from which it 

 moves in the opposite direction at the beginning of the dicrotic incisure. 

 A pulse-record from this instrument consists chiefly of a large systolic 

 spike and a small inverted spike at the dicrotic notch, as represented 

 by a specimen record in figure 29 (opposite page 171). 



The only limitations to the accurate reading of such records are 

 their length and the care of the reader; the points are clearly enough 

 marked to read thousandths of a second. In the records at our disposal, 

 however, the speed of the photographic paper was adjusted for reading 

 not closer than 0.005". 



Pursuant to the theory of Hunt, a number of our temporal-pulse 

 records were re-read with reference to the relative length of systole and 

 diastole. The records that we happened to read first were those of 

 Subject III and they will serve very well as an illustration. Three 

 records from the normal rest pulse of Subject III on March 9 gave the 

 following averages: 



5 h OO m p. m. Av. systole 313(7. Av. diastole 556 a. 

 6 00 p. m. Av. systole 315 <r. Av. diastole 639 a. 

 6 35 p.m. A v. systole 301 <r. Av. diastole 781 <r. 



In this normal session the retardation of the pulse, amounting to 42 

 per cent, was entirely due to longer diastole; that is, according to the 

 theory of Professor Hunt, the retardation was chiefly or exclusively due 

 to increased action of the heart inhibitor, probably to increased vagus 

 tone. A conspicuously different picture is presented by records from 

 the alcohol day, February 9. One of the pre-alcohol records, record 1, 

 showed at 4 h 15 m p.m., average systole 278cr; average diastole, 407 a. 

 Twenty minutes after dose B of alcohol, at 



5 h 20 m p. m. Av. systole 278 a. Av. diastole 515(7. 

 6 30 p.m. Av. systole 300 <r. Av. diastole 543(7. 



That is, after alcohol an increase in diastole of about 33 per cent corre- 

 sponded with an increase in systole of about 8 per cent. This appears 



