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SCIENCE 



[N. S. Vol. XLIII. No. 1122 



emphasized by Sherrington and has been 

 given special attention by Dodge. It is 

 relatively impossible to control voluntarily 

 the rate of moving the eye from one point 

 to another, as this invariably results in an 

 intermittent motion. By having two fixa- 

 tion marks and, on signal, moving the eye 

 as rapidly as possible from one to the other, 

 a photographic record was made of the 

 eye movements. The time is recorded di- 

 rectly on the plate as in eye reaction rec- 

 ords, by means of the light interrupter. 

 From this record we count up directly the 

 number of hundredths of a second required 

 for the eye to move through this are of 40°. 

 This time or velocity measurement is the 

 l)asis of our discussion. Of course the 

 record indicates the accuracy with which 

 'the eye looks at these two marks and also 

 the number of times that the eye moves 

 from mark to mark. This technique has 

 proved most satisfactory. 



Since eye movements are not well adapted 

 to show the rapidity of free oscillation, as 

 successive eye movements are separated by 

 moments of fixation, we adopted the recip- 

 rocal innervation of the middle finger for 

 measuring the speed of alternating recip- 

 rocal innervation of antagonistic muscles. 

 The finger movements were recorded in the 

 following manner : 



A very light lever, the weight of which 

 was not borne by the finger, but held by a 

 pivot, was attached to the middle finger of 

 the right hand and the projection of the 

 lever placed opposite the slit of a photo- 

 graphic camera, so that the shadow of the 

 lever could be photographed directly. At 

 the same time electrocardiograms were 

 taken from body leads, thus giving the 

 pulse rate ; a respiratory curve and the time 

 in seconds were simultaneously photo- 

 graphed. The number of finger movements 

 during the first, second and third 2-second 

 periods were the basis for discussion. Even 



in this short time distinct evidence of 

 fatigue was noted. 



With these important measurements of 

 simple and complex processes, memory, 

 electrical threshold, eye movements, and 

 finger movements, a large number of pulse 

 measurements were taken throughout the 

 series of observations. After making tests 

 with various forms of apparatus, we finally 

 relied entirely upon electrocardiograms 

 taken from body leads, two electrodes being 

 attached to the chest, thus leaving the sub- 

 ject entirely free and untrammeled for any 

 other simultaneous tests. The electrocardi- 

 ograms were obviously not taken for diag- 

 nostic purposes and have value here as 

 showing only the pulse rate. As the meas- 

 urements were made not only during the 

 mental work, but during moderate amounts 

 of physical exercise, such as finger move- 

 ments, rising, and two genuflections, the 

 data obtained permitted us to draw con- 

 clusions regarding the heart rate during 

 moderate mental and physical work. 



In considering all of our experiments it 

 is important to note that the processes 

 selected for measurement are, we believe, 

 for the most part remote from voluntary or 

 conscious modification or control. The pro- 

 gram was quite varied, the subjects passing 

 from one series of tests to another, yet the 

 apparatus was so disposed in the laboratory 

 as to necessitate a minimum amount of ex- 

 traneous muscular movement in changing 

 from one position to another. Special care 

 was taken to have the whole atmosphere of 

 the laboratory quiet and serene. 



The problem of collecting subjects for a 

 research of this kind was by no means 

 simple. It was finally decided that a good 

 degree of intelligence was necessary for 

 proper cooperation between subject and ex- 

 perimenter ; furthermore, the moral respon- 



