The Reaction to Tactile Stimuli 
251 
Column G. The time during which the embryo is considered as 
moving its head regularly away from the side touched. 
Column H. The number of responses given during the period 
represented by Column G. 
Column L The percentage of the responses indicated in Column 
H that were away from the side touched. 
The time is recorded in each instance in hours and minutes, ex- 
cepting in a few instances in Column B where the time was not 
determined. Averages are given in the several columns for each of 
the three types, excepting in Column H where the corresponding 
numbers represent totals. 
With reference to the side touched in each trial my records are 
complete, but, inasmuch as the records in Column G clearly have 
no references to the side touched as determining factor, this 
element of the question is omitted from the table. 
A comparison of the averages in Column B of the table might be 
interpreted to mean that the specimens of the second and third type 
came under observation relatively earlier in the period of develop- 
ment than did the specimens of the first type. But it should be 
noted that the figures in Column B represent the maximum 
possible time of irritability before the observation of it began. On 
the other hand, a comparison of the averages in Column G shows 
a clear distinction between Type I, on the one hand, and Types II 
and III, on the other. There is a difference of, say, 10 to 15 hours 
in the length of the period of regularity in moving the head away 
from the side touched. Furthermore, if the average of Column G 
for Type I be compared with the corresponding average for Type 
II plus the averages of Column E and F of this type, it will be seen 
that the embryos of Type I were longer in passing through the one 
period of regularity than were the embryos of Type II in passing 
through the periods of both regularity and irregularity, including 
the interval. It would seem, therefore, that a period of irregular- 
ity has not been passed over unobserved in Type I, and that the 
distinction between these two types is not based on the relative 
age of the individuals when they came under observations. 
A similar comparison of the corresponding figures for Type III 
with those of Type I shows that the time represented by Columns 
E, F and G for Type III approximately equal that of Column G 
for Type I. But for the excessively long period of No. 38 in 
Column G, the comparison would result about the same as that 
