Average of 10, 168.3[sigma] Average of first 5, 159.2[sigma]
  Average Variation, 16.64[sigma] Average of second 5, 177.4[sigma]

Both are fairly representative series.  They show the extremely large variations, in the case of series 1, from 102 to 179[sigma].  In all these experiments such variation is unavoidable because it is impossible to have the conditions uniform.  A very slight difference in the frog’s position, which could not be detected by the operator, might cause considerable difference in the time recorded.  Efforts were made to get uniform conditions, but the results seem to show that there is still much to be desired in this direction.

Tables VII. contains the results of four series of ten reactions each for frog A.  It will be noticed that the time for the first five in each series is much shorter than that for the last five; this is probably indicative of fatigue.

TABLE VII.

REACTION TIME OF FROG A TO ELECTRICAL STIMULI.

Series of       Averages     Averages of     Averages of
ten reactions.     of series.   first five.     second five.
1            163.1[sigma] 134.6[sigma]   191.6[sigma]
2            186.2         176.2           196.2
3            161.1         125.2           197.0
4            158.3         101.6           215.0
General averages    167.2[sigma] 134.4[sigma]   199.9[sigma]

TABLE VIII.

REACTION TIME OF FROG B TO ELECTRICAL STIMULI.

1            132.7[sigma] 118.2[sigma]   147.4[sigma]
2            196.6         167.8           225.4
3            147.4         145.5           149.8
4            157.5         152.0           163.0
General averages    158.6[sigma] 145.9[sigma]   171.4[sigma]

TABLE IX.

NORMAL AND REFLEX REACTION TIME OF SIX ANIMALS TO ELECTRICAL STIMULUS.

Normal.  Reflex. 
Average for 20 Average for 20
Frog. reactions.  Mean Var. reactions.  Mean Var.
A 149.5[sigma] 24.0[sigma]
B 158.3 16.0 51.5[sigma] 8.0[sigma]
C 191.0 24.3
D 167.0 10.1
E 182.4 28.0 45.1 5.5
F 176.3 10.2 46.0 4.5
General
Average. 167.9[sigma] 18.8[sigma] 47.5[sigma] 6.0[sigma]

   For D the average is for ten reactions.

   B and E were males, F a female; the sex of the others was
   not determined by dissection and is uncertain.