pt eee a_i tems 
PREOVIPOSITION PERIOD OF THE HOUSE FLY. 9 
Taste III.—Correlation between the average mean temperature and the length of the 
preoviposition period of the house fly. 
Average Length of the preoviposition period in days. 
mean tem- 
peratures 
eer 213141516178 9|10|11}12] 13/14/15] 16] 17] 18] 19| 20] 21] 22] 23 
82° to 84°..] 1 |.-- 
To represent this relation graphically the average of the average 
mean temperatures for all the records of a given length has been taken, 
and the following figures obtained: 
Length of | Number of Average of the 
period. records. fan eratiies: 
Days. OM 
24 i 82.5 
3 3 80.9 
4 4 79.5 
5 3 79.2 
6 6 74.9 
7 1 78.5 
8 2 doe2, 
9 10 ie 
10 4 67.1 
11 6 65.8 
12 8 68.1 
13 i 67.3 
14 9 63.9 
15 1 66.7 
16 2 68.8 
17 5 65.8 
18 1 59.1 
19 2 62.3 
20 i 63.5 
22 1 61 
23 1 65. 1 
Figure 1 shows the curve obtained by plotting these figures. The 
broken line in the figure is the hyperbole which is the nearest approach 
to the actual experimental curve. If it is true that “‘the curve 
expressing the increase in rate of development is a true hyperbole”’ 
(Peairs, 1914), one must seek for an explanation of the many devia- 
tions from the true curve which are seen in the experimental curve. 
It is of course probable that if the accumulated effective temperature 
for each period were worked out, the resulting curve would-show a 
much closer approach to a true hyperbole. 
