389 



W 15 20 is io 55 io Vs so 55 60 6S 



is BO b5 So SS ico liH 



Pig. 15. Equal-velocity chart for the pupal stage, with lines CD, DD, BD, 

 AD, BW, and AW showing the daily march of temperature and humidity in 

 the variable-temperature experiments of the same designation. The shaded 

 area covers medial conditions, that is, conditions within the straight-line limits 

 of the velocity curve. (See Table XVIII, p. 398.) 



