616 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



previous dates. The change is very similar to that which occurred 

 in the second experiment with Squad A. On the last date for Squad 

 B, January 27, the normal level was reached, but Squad A was not 

 quite at their normal level in the last experiment. 



The data with both squads appear to indicate that, coincident with 

 the beginning of food reduction, the electrical threshold was in- 

 creased in the neighborhood of 15 per cent, while the standard devia- 

 tion and percentage of variability show no concomitant change. 

 Threshold determinations on Squad B indicate what might reasonably 

 be expected, i. e., some improvement with practice. It would be sur- 

 prising if the physiological threshold were reached without practice in 

 this case of electrical stimulation. Squad A shows no such improve- 

 ment with practice, and this lack we associate with the reduced 

 diet. 



(14) SPEED OF THE EYE MOVEMENTS. 



Of the measurements at present available, the motor coordination 

 for successive horizontal eye movements is one of the best ndicators 

 of the neuro-muscular condition.^ The finger movements, as a motor 

 process, compare very favorably with the eye movements, but in the 

 case of the latter it is not so possible, if indeed it is at all possible, for 

 the subject to influence them voluntarily. The time required for 

 making a horizontal sweep of the eye through 40° on the arc of vision 

 is almost a neuro-muscular constant for the individual and for his 

 physiological or neuro-muscular condition. 



Eye-movement records were taken with 63 men in the normal series 

 of 1917. They were all recorded from the right eye and with the left 

 eye covered.^ The procedure was identical with that used in the low- 

 diet research. Four series of records, i. e., two plates (for illustrative 

 records, see fig. 52) were made with each subject, as in the present 

 investigation. The number of eye movements left or right which are 

 available for counts in the case of a particular subject is usually 20. 

 Therefore, the average figure for any man on any date is usually drawn 

 from this number of counted movements. The range of eye-move- 

 ment speed shown by the men in the normal series of 1917 is tabulated 

 in table 179. The units are 0.001 second (cr) and the column headings 

 in the table are self-explanatory. Two subjects show speeds for move- 

 ments to the left which average 76 and 79 a, respectively. These fall 

 in the group division 71 to 80. The slowest eye-movement times for 

 left movement were the averages 141 and 148. The distribution 

 between these high and low points is fairly characteristic of normal 

 frequency. The mode is clearly at 101 to 110, 24 of the 63 subjects 

 showing averages which came within this range. The total average 

 for the left movement is 107.0 a and the standard deviation for the 



^Dodge and Benedict, Carnegie Inat. Wash. Pub. No. 232, 1915, pp. 146 and 262. 

 'There were a very few exceptions to this latter statement due to errors in the procedure. 



