40 



BULLETIN 700, U. S. DEPARTMENT OF AGRICULTURE. 



data given for each station represent slightly different numbers of 

 days. In figure 19, as well as in certain other graphs, the curves are 

 comparable in each case as to direction of slope; but it should be 



16 



15 



14 



13 



IZ 



10 



IS 26 



\ 





\ 





\ 





\ 







1132 









1938. 2 



\ 



\ 



\ 



+330 



N 

 — _\ 



\ 





\ 3932 



\ 



^ -^^ 









\ 



\ 

 \ 



^ ^ 



685 

 3285 





\ 



tO 25.8 s 











^v 









^ 



\ v 









II . - ^ 



436. / 











8/1 



Days 10 L 



Days 



65 L 



hys 



Oak-Brush Type 



Aspen- Fir 



Spruce-Fir 



Temperature Above 40' F 



Sum Of Daily Means 



Physioloaical Temperature Efficiency 



Fig. 20. — Temperature efficiency summations for period of growth of special experiments. 



understood that the lengths of the ordinates are not in all cases di- 

 rectly comparable ; the vertical scales employed are merely convenient 

 ones and are quite arbitrary. 



