SEXUAL ACTIVITY OF MALE RABBITS 483 
TABLE 3—Continued 
DATE TEMPERATURE Ist 5TH 10TH 15TH 20TH 
Male 6 
6-15 23 0.030 0.020 0.034 0.010 
6-28 27 0.025 0.040 no prog. 
IMiGan Steer os seers oitieree ok 0.0383 0.027 0.022 0.025 0.019 
Standard deviations 
Ofameansie eee ase 0.0034 0.0049 0.0045 0.0068 0.0062 
Standard deviations 
of differences ....... 0.0058 0.0067 0.0081 0.0092 | 
been a factor which we were unable to control. The diluent, 
glassware, etc., remained at room temperature, which varied 
widely by days and by seasons, but almost in every case the 
readings on the various services of a given series were made at 
temperatures which did not vary more than one or two degrees. 
Under the circumstances the best that could be done was to re- 
cord the temperatures at each reading, and these are set down 
in the table. Unless at least two readings at different services 
within a given series were obtained they were not set down in the 
table, consequently many readings on rate which were made are 
not there meluded. 
The data on rate of motion are given in table 3. Specimens 
which showed no sperm making progressive vibratile motion 
although other types of motion were present are recorded as ‘no 
prog.’ The means, their standard deviationsand the standard 
deviations of the differences between contiguous means are set 
down. The slight downward trend of the mean rates as the 
service number advances, when studied in connection with 
standard deviations, is seen to be wholly without significance. 
In every case, except the Ist and 5th, the standard deviation 
of the difference between the means is actually greater than the 
differences themselves, whereas if these differences are to be sig- 
nificant the standard deviations should be not more than one- 
third the latter. These meager results suggest that a certain 
velocity is characteristic of progressive vibratile motion. If the 
energy of the sperm becomes spent so that this velocity cannot 
