PULSE-RATE. 393 



diet. On January 14 all the men except Sne showed a reduc- 

 tion in pulse-rate from the basal values found on January 6, this re- 

 duction for the squad as a whole averaging 8 beats. On January 20 

 a further reduction was noted in all but two cases, Lon showing no 

 change and Ham showing an increment of 2 beats per minute. The 

 average decrease for the entire squad was 5 beats. On January 28 

 a still further reduction was noted. On the average it decreased from 

 43 to 40, although with 3 individuals the pulse-rate increased on this date. 

 At the bottom of table 82 are given both the maximum and minimum 

 values, together with the differences. The average difference between 

 maximum and minimum is 18 beats, showing for this squad a max- 

 imum decrease in the pulse-rate of 18 beats. This is in full conformity 

 with the picture presented by the extensive data with Squad A. 



STANDARD ELECTROCARDIOGRAMS. 



The pulse-rate data, which have been presented and discussed in 

 preceding pages, were in all cases recorded from counts at the wrist. 

 During the collection of these data, no subject or observer ever noted 

 irregularity at the time of making the pulse counts. There were no 

 apparent cardiac symptoms, even after hard muscular work. (See 

 page 453.) The pulse-rate appeared to decrease with fair regularity 

 with the progress of the experiment. It seemed highly improbable that 

 the slow rates of 35 or less were due to disturbances in conduction such 

 as a regular 2 : 1 heart block, i. e., failure for every other auricular 

 impulse to get through to the ventricles, or to the complete dissocia- 

 tion of auricles and ventricles characteristic of the Stokes-Adams syn- 

 drome. In the latter case, it is well known that the independent rate of 

 the ventricles is usually about 32 per minute. Convincing proof in this 

 matter of the normality of heart action in these slow pulse-rates asso- 

 ciated with reduced diet could of course be had through graphic records, 

 such as electrocardiograms taken under standard conditions. 



It was desirable to interfere as little as possible with the Boston 

 experimental program. This work could not be done in Springfield, 

 and rather than take electrocardiograms from every subject, it ap- 

 peared more satisfactory to take such tracings from only the 4 or 5 

 subjects who showed the slowest pulse-rate. Connections were there- 

 fore arranged from the string galvanometer in the main psychological 

 laboratory to the group respiration chamber in the calorimeter room. 

 The electrodes used in the respiration chamber were of the non- 

 polarizable, wick form. A long strip of cotton gauze soaked in a saline 

 solution was wrapped about the arm and the end of this dipped into a 

 vessel of the saline solution. The distance between the arm and the 

 vessel was about 7 inches. A porous clay cup containing the amal- 

 gamated zinc electrode and zinc sulphate was also placed in the vessel of 

 sahne solution. Such electrodes were connected with each arm, while 



