SUMMARY 251 



specimens has been shown to be 71*1, while that for the 

 winter-specimens was 39-9, the relative photosynthetic 

 activities in spring and in winter being as 71 • 1 : 39 • 9 (p. 120). 

 The ratio of tonicity in spring to that in winter has been 

 shown to be as 1 -8 : 1. The ratio of activity A to tonicity P 

 is : 



Activity for C0 2 -concentration A s for spring 7I . T 



=— = 3Q • 9 



Tonicity for spring P s 1 • 8 



Activity for C0 2 -concentration A w for winter ->q-q 

 Tonicity for winter P w 1 



39'9 



Hence the law of photosynthesis for variation of tonicity is 

 that the ratio of activity to tonicity is a constant. 



— is a constant. 



Summary 



On the physical scale for variation of temperature, the 

 expansion-curve of permanent gases, when produced back- 

 wards, cuts the abscissa at the absolute zero. The volume 

 of a given quantity of gas under constant pressure is found 

 from the relation 



V 



= which is a constant. 



On the physiological scale, the straight part of the curve 

 in the median range when produced cuts the abscissa at a 

 point which is taken to be the physiological zero. A simple 

 relation is then discovered between the variable factors as 

 measured on the physiological scale and the resultant change 

 in the photosynthetic activity. 



It is shown for temperature, C0 2 -concentration, light 

 and tonicity, that the ratios to activity 



A A A A 



-> -> j-» p are constants. 



