391 



to the greater amount of low temperature. The curve for the lower 



temperature data was then changed to y 

 which fitted the data. 



10 



K, giving a curvature 



FixAL Correction of the Equal- Velocity Chart. 



\Mth the equal-velocity chart thus revised, the entire record of 

 variable-temperature experiments on pupae was worked over, in order to 

 check the values on the chart. Table XVII indicates the ditTerence be- 

 tween the substitution-quotients used for this purpose and the uncorrected 



Table XVII. Showing substitution-quotients for variable temperature experi- 

 ments, in comparison icith other methods of calculation. 





Z '^ o 



First (ieneraticin 1917 



* It is not possible to determine a fair alpha value in these cases. Various alpha 

 values and cur\'es were tried until a substitution-quotient of 270 was approximated. 

 Note development below alpha In RWA. The day degrees ma.v be derived by subtract- 

 ing the alpha value from mean temperature and multiplying by days because the 

 means are based on actual hours. 



Note: When the substitution-total is correct, it Is numerically the same as 1/24 

 the total of developmental (hour) units as defined on p. 332. 



sums of "efifective temperatures." Note that the difference amounts in 

 some cases to thirty or more units. See also Tables XVIII-XIX. 



In order to check the equal-velocity chart still further, our outdoor 

 and greenhouse observations on pupae at Champaign and Glenn's obser- 

 vations on pupae at Olney were entirely worked over (except where 

 hygrothermograph records were missing for part of 1917). The two-hour 

 temperatures and humidities for the entire periods in which pupae were 



