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AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



could be done by voluntarily contracting the flexor muscles of the index 

 finger before the first failure to respond to a voluntary stimulus appeared, then 



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Fig. 120.— A record of the extent of the flexions of the forefinger lifting a weight at regular intervals. 

 The light lines are those for the voluntary contraction ; the heavy lines, those for contractions following 

 the direct stimulation ofthe flexor muscles by electricity. In the former then- are periods, in the latter 

 none. The arrow shows the direction in which the record is to be read (Lombard i. 



the curve expressing this capacity for voluntary work throughout the day 

 was represented as in Fig. 121. Briefly, the curve shows two maxima, at 10 

 P. M., and 10 a. M., with two minima midway between them. In general 



Fig. 121.— Showing at each hour of the day and night how many centimeters a weight of 3000 grams 



could be raised by repeated voluntary contractions ofthe forefinger before fatigue sets in. The curve is 

 highest at 10 to 11 a.m. and 10 to 11 p. m.; lowest, 8 to 4 p. m., and 3 to 4 a.m. circle with dots, observa- 

 tion made just after taking food; square with dot, smoking ; *, work done 8 minutes after drinking 15 

 c.c. of whisky ( Lombard i. 



the immediate effect of taking food is to increase the work done by the sub- 

 ject. Alcohol lias the same effect, while smoking produces a decrease. 



Further, from day to day this capacity for work is influenced by a num- 

 ber of external conditions — temperature, barometric pressure, etc. 



