The Bulletin 
59 
larities would cumulate, and while individually they might be insignifi¬ 
cant, yet when added to each other they have a tendency to throw our 
results away from the mean. 
DURATION OF MOLTS 
(Second Molt, Fig. 20 ) 
There are two standards by means of which we may measure the 
duration of the second and succeeding molts. The first is the time that 
has elapsed since the first molt, and the second is the time that has 
2 3 4 5 6 7 8 9 101112 
Figure 32. Curve showing the time lapsing between hatching and the first 
mojt, one-day intervals. The mean time is shown by the dashed vertical 
line (-—-). 
elapsed since the egg hatched. Both of these methods have been used 
and the results expressed graphically by the attached curves (Figs. 33 
and 34). 
The time elapsing between the first and second molts is comparable 
to the time elapsing between hatching and the first molt, the range 
extending from 2 to 13 days. The majority, 106 out of 134 or a little 
more than 79 per cent, however, molted the second time from 3 to 6 
days after the first molt. 
The duration in days from the time of hatching to the second fnfrlt 
is not nearly as uniform as it is in the first molt, the range in 175 larvae 
being 6 to 21 days. However, 140 larvae out of the 175 observed molted 
a second time between the sixth and eleventh days, making a total of 
