94 Effect of Alcohol on Psycho-Physiological Functions. 



to drag over the surface of the revolving belt, satisfactory photographic 

 records were obtained, although but few such records are reported in 

 their data. Professor H. Monmouth Smith, of the Nutrition Labora- 

 tory, has made extensive use of this method and has accumulated a 

 large amount of data on the pulse rate during walking. Dodge and 

 Benedict 1 called attention to the unique advantage of the body-leads 

 for leading-off electrodes in taking electro-cardiograms during muscular 

 activity. Since these are " situated directly over relatively small 

 trunk-muscles, even violent activity need not interfere with the rec- 

 ords." Recently Krogh and Lindhard, 2 assisted by Fridericia and 

 Westerlund, made some determinations of the pulse rate while the sub- 

 ject was working on an ergometer, recording the pulse by means of a 

 string galvanometer. For electrodes wet bandages and thin copper 

 wire were wrapped about the wrists. 



Our own experimental conditions may be more clearly understood in 

 connection with a description of the illustrated records (see fig. 11). 

 After the finger movements the subject leaned back in the steamer 

 chair and was told to relax as much as possible. No adjustments were 

 necessary, as he was already connected to the string galvanometer for 

 pulse observations and also with the apparatus for recording the 

 respiration rate. After approximately 60 seconds, or longer if the 

 operator saw by the deflections of the string that the subject's pulse had 

 not become regular, the record was begun. (See left-hand end of 

 record, A in figure ll.) 3 After 8 or 10 seconds the signal "go" was 

 given forcefully by the operator. At this signal the subject volun- 

 tarily contracted the muscles of arms, legs, and trunk, and retained this 

 condition of tension until the signal "stop," at which he fell back in the 

 chair and remained quiet. The beginning of voluntary contraction 

 (see the vertical line drawn near the left end of the record) and the 

 interval of its duration are clearly shown. The action currents asso- 

 ciated with the general muscle contraction produced in the pulse 

 tracing a prominent deflection of the galvanometer record. Further- 

 more, the setting of abdominal muscles caused a marked disturbance in 

 the respiration curve. The pulse curve was continuously disturbed 

 during the interval of tetanus by the action current from contracted 

 muscles. However, the sharp spike of the R wave 4 of the electro- 

 cardiogram complex is clearly visible. The cessation of contraction is 



1 See Dodge and Benedict's report, p. 193. 



2 Krogh and Lindhard, Journ. Physiol., 1917, 51, p. 182, see p. 186. 



3 The camera had been in operation for some seconds previous to the beginning of the photo- 

 graphic record in order that the actual commencement of the record should not attract the atten- 

 tion of the subject, who was within a few feet of the apparatus. (See Dodge and Benedict's 

 report, fig. 1, position 1, p. 31.) 



4 Standard electro-cardiograms are always read from left to right. The deflections which are 

 above the base line (positive variations) have by Einthoven been termed P, R, T, and U. The 

 sharp R wave very slightly precedes active ventricular contraction. For fuller explanation of 

 terminology, time relations, and interpretation of the electro-cardiogram waves, see Wiggers, 

 Circulation in health and disease, Philadelphia, 1915. 



