256 CHAP. XXVII. SIMULTANEOUS VARIATION OF FACTORS 



Activity 



(a) Light 500 lux, C0 2 -concentration 3 -5 mg.; 172 -8 c. mm. O 



(b) „ 1000 „ „ 3-5 „ ; 333-0 „ 



( c ) » 500 ,. „ 7'° » ; 304*2 



{d) „ 1000 „ „ 7-0 „ ; 583-8 „ 



From (a) and (b) we obtain the partial effect of light : 

 Activity at 1000 lux _ 333 



Activity at 500 lux 172-8 



= 1-927 . . . (1) 



From (a) and (c) we obtain the partial effect of C0 2 -concen- 

 tration : 



Activity for C0 2 -concentration 7 . _ 304 • 2 _ ,- , > 

 Activity for C0 2 -concentration 3 • 5 172-8 



The theoretical enhancement of activity by the com- 

 bined effects of increase of light and C0 2 -concentration (from 

 500 to 1000 lux and from 3-5 to 7 mg. C0 2 -concentration) 

 should, according to the Law of Product, be (1) X (2) times 

 the original activity 172-8 c.mm. 



The theoretical result is then 



1-927 X 1-76 X 172-8 = 585-79 c.mm. 

 Observed result (d) = 583-80 



The agreement between the theoretical and experimental 

 results is very remarkable. 



From the above results we find that 



A L c=A/ c |/(l)x/(c)} 



where A LC is the enhanced activity under the combined 



effects of stronger light and C0 2 -concentration ; A/ c is the 



original activity at lower intensity of light and C0 2 -con- 

 centration ; / (l) and / (c) are the partial factors for light 

 and C0 2 -concentration. 



The resultant effect of the simultaneous variation of different 

 factors is thus the product of their partial effects. 



