THE PHYSIOLOGICAL ZERO 



245 



different from that at which photosynthesis becomes arrested. 

 We obtain the absolute physiological temperature, indicated 

 by the thick type T, by subtracting 9°-2 from the tem- 

 perature on the centigrade scale. For example, when the 

 physiological zero is at 9°-2, a temperature of 21 C, 

 converted into the absolute physiological scale, becomes 

 21 — 9 -2 = n° -8 = T. I will use the term absolute 

 determination when measurements are made on the physio- 

 logical scale. 



In illustration of the advantages of the physiological 

 scale, I give determinations of the coefficient for tempera- 

 ture in the following table, the data being those of the 

 typical specimens I. and II., previously given in Table XIX. 



Table XXXIV. — Physical and Physiological Scales and the 

 Determination of the Temperature Coefficient 



Absolute determination of the coefficient 

 Examples. 



Specimen I. Physiological zero . . 9°-2 



(a) Temp. I7°-5C; T=i7'5- 9' 2==8 '3 : activity =168 -i 



K=20-25 



(6) Temp. 24°-5C. ; 1=24-5 -9 -2 =15 -3 : activity =318 -2 



K=20-8 



