214 



ENVIRONMENTAL CONDITIONS. 



curve, which was continued at either end to cut the axis of abscissas 

 at 2° and 48° C. The ordinates corresponding to the various abscissal 

 temperature values were then actually measured. Finally, all the new 

 ordinates thus derived were expressed in terms of the ordinates for 

 40° F. considered as unity. The resulting series of values are Liv- 

 ingston's physiological indices of temperature efficiency. He presents 

 a table showing these values for each single degree of temperature from 

 36° to 118° F., and that table is here reproduced as our table 5. 



Table 5. — Physiological indices of temperature efficiency for growth, based on Lehenbauer's 



12-hour exposures with maize seedlings. 



