244 
In computations for Table 4, 50 was taken as the zero of develop- 
ment and 85 as the degree of maximum rate of development. The results 
indicate that 52 degrees would have more nearly satisfied the conditions ; 
but as the main interest in this table is that it gives an opportunity for 
comparing the rate of development of larve in apples on the tree and in 
picked apples, in order to have the same units of accumulation in both 
cases 50 was used as the zero. The average accumulation of effective 
day-degrees required to develop larve in picked apples was 587, or 86 
day-degrees less than for larvee in apples on the tree (Table 3). 
The variations in the length of the larval period are very great for 
individuals even when subjected to the same conditions. The following 
example will illustrate the extent of the variations. Of 19 larve hatched 
July 20, 1916, one pupated in 20 days, two in 23 days, three in 25 days, 
one in 27 days, three in 28 days, four in 29 days, three in 30 days, one 
in 31 days, and one in 34 days, giving a variation of 14 days in the length 
of the period. Individual variations are also shown by the varying num- 
ber of effective day-degrees which accumulated during the larval period. 
Tables 5 and 6 show the distobasion of larve as to accumulated 
effective day-degrees. 
TABLE 5—DIstTRIBuTION OF LARVAE REARED IN APPLES ON THE TREE WITH REFER- 
ENCE TO ACCUMULATED EFFECTIVE DAY-DEGREES DURING THE PERIOD 
Number of larve Range of effective day-degrees 
8 f 456-499 
18 500-549 
» 39 550-599 
65 600-649 
64 650-699 
58 700-749 
29 750-799 
26 800-849 
16 850-899 
6 900-949 
1 950-969 
The variations above 900 and below 500 are possibly due to errors in 
observations. The smaller variations are due in part to the use of the 
day as the period unit, and in part, no doubt, to the various temperatures 
