- 248 - 



The loss of dry matter by respiration can not be estimated 

 accurately. From the figures given on page 242 it may be calcu- 

 lated that the daily loss of dry matter is 7.1 % of the dry matter 

 of the leaves and 2.4 % of the dry matter of the stems. For one 

 week the figures are about 50 % and 17 %. Now Hornberger 

 has estimated the dry matter in the Sinapis plants from week 

 to week; hence it is possible to make an approximate estimation 

 of the loss of dry matter. From this it can be calculated that the 

 loss of matter by respiration will be about 10.000 kg, but the value 

 is uncertain. Then the total production of dry matter would be 

 ca. 20.000 kg per ha. Only 1—2000 kg (10—20 %) are seeds. 



5. The production of matter in shadow plants. 



In a similar manner I have estimated the production of mat- 

 ter in shadow plants. I chose the following four plants for my ex- 

 periments, viz. Oxalis acetosella, Ajuga reptans, Senecio silvaticus 

 (shadow plants) and Sambucus nigra (shadow leaves). As a rule 

 the leaves used in the experiments were grown in a light intensity 

 as small as possible. 



I 



§ 8h 



24 



1 1 — 1 ' 



Fig. 7. C0 2 assimilation in Oxalis acetosella, Senecio silvaticus, 

 Sambucus nigra and Ajuga reptans. 



1. G0 2 assimilation. The "results of the estimations are given 

 in the tables V — VIII and in the curve fig. 7. The curves for the 

 three plants are practically identical. 



The values for the three cardinal points are the following: 



