56 PLANT RESPIRATION 



Plant Material i/n 



Cotyledons of peas 0-83 



Cotyledons of peas o- 79 



Roots of Daiicus Carola o. 75 



Roots of Daucus Carota iio 



Roots of Daucus Carota o 80 



Roots of Daucus Carola o ■ 58 



Green grapes i • 3 



Green grapes i ■ i 



Blue grapes 12 



Blue grapes 12 



Blue grapes i • ° 



Blue grapes ©74 



Potato tubers o ■ 73 



Potato tubers 10 



Potato tubers o-44 



Potato tubers 0.93 



Potato tubers 11 



Leaves of Tropaeolum majus o- 55 



Leaves of Tropaeolum majus o. 56 



Leaves of Tropaeolmn majus o.^b 



Seedlings of Sinapis sp : 0.18 



Seedlings of Sinapis sp 0.21 



It is clear that such a weak alcoholic fermentation as takes 

 place in the above quoted plants with oxygen excluded does not 

 even approximately suffice for the normal living processes of 

 the plants. Theoretical calculations as well as direct calori- 

 metric determinations show that the best production of heat in 

 the fermentation of i mol of grape sugar is equal to 24-28 

 Calories, while the combustion of i mol of grape sugar in 

 respiratory processes yields 674 Calories. Consequently about 2 5 

 mols of sugar must be fermented in order to produce the amount 

 of energy which is formed by the combustion of i mol of sugar 

 in respiration. In fact such an increased consumption of sugar 

 takes place in the alcoholic fermentation by yeast plants but not 

 in the anaerobic respiration of seed-plants where the production 

 of energy is often 50 to 100 times less than under normal living 

 conditions. On account of the lack of working energy the 

 plants finally go to ruin if the temporary anaerobic condition 

 continues too long. Even after a short period of deprivation of 

 oxygen a poisoning of the research material is sometimes noted. 

 After the restoration of normal aeration the plants gradually 

 recover, since the substances produced in the absence of oxygen 

 are consumed in the processes of oxidation. 



