58 PLANT RESPIRATION 



tion remains constant (hence the plant material is not poisoned), 

 on the whole, various seedlings liberate equal amounts of CO2 

 at various temperatures. Since the rate of anaerobic respira- 

 tion is increased by raising the temperature, it is clear that the 

 paralysis of vital activity commences more quickly with high 

 temperatures than with low. This is illustrated by the follow- 

 ing data: 



Sl'dden Fall 



IN CO:-FOR- 



MATioN (with Total 

 Exp. ■ Oxygen Ex- CO2 



No. Seedlings of T. cluded)after Formed 



la Vicia Faba 20° 9 hours 218 cc.^ 



lb Vicia Faba 35° 6 hours 223 cc.^ 



2a Pisum sativum 20° 9 hours 154 cc- 



2b Pisum sativum 30° 6 hours 159 cc- 



2C Pisum sativum 40° 5 hours 159 cc- 



3a Pisum sativum 20° 7 hours 358 cc.^ 



3b Pisum sativum 35° 4 hours 366 cc.^ 



It must be taken into consideration that an increase of tem- 

 perature stimulates various material transformations in the 

 living cell. These more intensive vital operations require a 

 greater expenditure of energy. Since anaerobic respiration is 

 unable to produce a corresponding amount of energy, the cell 

 can prolong its life a longer time at a lower temperature than at 

 a higher one, for in the latter case the poisoning asserts itself 

 more rapidly through products of the imperfect metaboUsm. 



Palladin^ has shown that etiolated bean leaves increase the 

 formation of CO2 after an apphcation of sugar not only in the 

 presence but also in the absence of oxygen, and indeed in 

 exactly the same ratio. Consequently the value of I/N is not 

 altered by the application of sugar. This result cannot be 

 regarded as a chance agreement of the experimental data. 

 No less noteworthy are the results of Morkowin^ who found that 

 even such a temporary stimulation of respiration as is brought 

 about by toxic action does not alter the ratio I/N. The normal 

 respiration is thus increased by chemical stimulation effects in 

 exactly the same relative degree as the anaerobic respiration. 



1 Chudiakow, N. loc. cil. p. 381. 



2 Idem. loc. cil. p. 384. 



3 PaUadin, W. Rev. g6n. de bot. 6: 201. 1894. 



• Morkowin, N. Ber. d. bot. Ges. 21 : 72. 1903. 



