242 
higher temperatures were due to retarding temperatures or temperatures 
above the degree of maximum rate of.development. To find this point 
guesses were made and tried out to test their correctness. It was found 
that by using 85 as the degree of the maximum rate of development, and 
subtracting twice the average day-degrees above 85 (column 7) from the 
day-degrees above 50, we got a temperature factor (column 8) for each 
of the temperature groups which when multiplied by the period expressed 
in days gave the most nearly constant products (column 10) for the dif- 
ferent groups, the average for all groups being 673. 
This average may be taken as the approximate average of accumula- 
tions of effective day-degrees for the larval period of larve reared in 
apples on the tree. 
In Graph 4, the average’ daily effective day- degrees as recorded in 
column 8 of Table 3 were plotted against the reciprocals of the periods, 
with the result that the points in the upper part of the graph were brought 
nearly into line with the other points. 
3 
1 
OFS 
040 : 
ate zi 1 
pabee re Eaecan +. 
ia FES 
EECEEREE mrt 4 
eerie ate 
tif 
fat ; 
OF 2D GSO VZV FEE 0 Oa eee 
GrapuH 4. Larval period. Reciprocals of the periods plotted against mean 
daily effective day-degrees. Larve reared in apples on tree. 
The data secured from observations made on 214 larve reared in 
picked apples were treated in the same manner as the data for larve — 
reared in apples on the tree. A summary of the results is shown in ~ 
Table 4. ; 
