THE METABOLISM OF PLANTS. 



305 



atmosphere of nitrogen, and they further observed that 

 when a spadix was kept in a closed receiver containing 

 air, a high temperature was only maintained so long as 

 free oxygen was present : Eriksson found that the tem- 

 perature of seedlings, of flowers, and of fruits in an atmo- 

 sphere of hydrogen was only O'i 0-3 C. higher than that 

 of dead objects, whereas in air their temperature was very 

 much higher. 



De Saussure observed in the case of Arum maculatum 

 there was some relation between the evolution of heat and 

 the absorption of oxygen, but it was left for Garreau to 

 investigate this point with accuracy. He found, in a number 

 of experiments, of which an instance is given below, that, 

 in the case of the spadix of Arum italicum, the greater the 

 absorption of oxygen the higher the temperature. 



The mean temperature of the air was 18 C. 



V. 



20 



