249 — 





Respiration in 

 the leaves, mg 



pel I1UUI 



per 50 cm 2 



Intensity of light, 

 in which the G0 2 

 assimilation is 0 



The maximal 

 value of the G0 2 



o cci mi 1 a *M r*n Tior 1 

 cioollllllct HUH JJcI 



hour per 50 cm 2 



Sambucus nigra 

 (shadow leaves) 



Ajuga reptans .... 



Oxalis acetosella . . 



0.20 

 0.15 

 0.10 



0.3 

 0.1 

 0.2 



0.85 

 0.70 

 0.80 



It will be seen that the values are small compared with those 

 found for light plants. 



2. Respiration. The respiration in the leaves of the three sha- 

 dow plants varies from 0.1 — 0,2 mg C0 2 per hour per 50 em 2 . 



Mayer (1892 p. 203, 441), who has previously investigated 

 the respiration in leaves, found for shadow plants the following 

 values : 





Oxygen con- 

 sumption per 

 1 g dry matter 



Tp. 



Respir, in mg 

 GO ? per 1 g 

 dry matter 

 (20°) 



Melampyrum pratense 



0.86 

 0.50 

 1.2 

 0.42 



21.7 

 21.8 

 22.0 

 16.0 



1.54 

 0.90 

 2.12 

 1.11 



The figures in the last column have been calculated on the 



CO 



supposition that the value of the quotient -q^ is 1. 



Calculating from my own estimations on Oxalis in the same 

 manner we will find that the leaves of this plant produce 1.44 mg 

 C0 2 per 1 g dry matter. 



In the rhizomes and leaf-stalks of Oxalis acetosella the respi- 

 ration was estimated to 0.20 mg G0 2 per lg per hour (20°). 



3. Percent production of matter. We will now try to 

 calculate the percent production in Oxalis in the same manner 

 as in Sinapis. The calculations are carried out for a plant with a 

 leaf area of 100 cm 2 (upper + lower surface). The weight and dry 

 matter content in such a plant are as follows. 



Weight dry matter 



Leaves 0.52 0.069 



Leafstalks + rhizomes ..... 0.85 0.165 



1.37 0.234 



Botanisk Tidsskrift. 36. Bind. 17 



