166 



PROCESS OF NUTRITION. CHAP. III. 



another receiver, no futher change is produced in 

 the volume of its atmosphere ; and consequently no 

 further inhalation of oxygene. But if it is allowed 

 to remain some time in the open air it inhales 

 oxygene as before. But the quantity of oxygene thus 

 inhaled is always inferior to the volume of the root. 

 A Radish, which consumed in the space of 24 hours, 

 a quantity of oxygene equal to its own volume, in- 

 haled one-fourth part. But a Carrot, which con- 

 sumed in the same space of time, a quantity equal 

 to its own volume, inhaled only ^-fa part. And a 

 Potatoe, which consumed only O*04 of its own 

 volume, inhaled only O'OS. 



This regular inhalation of a quantity less than the 

 root, with the faculty of inhaling oxygene anew after 

 a short exposure to the open air, seems to prove 

 that the root does not immediately assimilate the 

 oxygene which it inhales, but converts it into car- 

 bonic acid gas, which the atmospheric air again ab- 

 stracts. Thus the action of oxygene on the root, 

 whether in the sun or shade, resembles its action 

 upon leaves vegetating in the shade ; though in the 

 former case, the inhalation is less perceptible. 

 Roots therefore do not evolve oxygene at all. 



But if the experiment is made upon roots to 

 which the stem is still attached, the result is very 

 different, at least if the root only is confined in the 

 receiver, while the stem and leaves are left exposed 

 to the open air. For, in this case, the root seems to 

 inhale more than its volume of oxygene gas ; though 



