PLANT RESPIRATION 



found in plant respiration. Saussure also considered the for- 

 mation of water in plant respiration and explained in an excel- 

 lent manner the vital significance of the entire process. This 

 investigator is really to be regarded as the founder of the science 

 of plant respiration. 



Respiration continues without interruption during the life of 

 the plant and accordingly involves a considerable consumption 

 of the organic working materials {Betriehsmaterials). Full 

 grown green plants make up this loss by the process of photo- 

 synthesis, while the chlorophyll-free lower plants replace this 

 material by means of nutrients absorbed from their environ- 

 ment. However, in germinating seeds, which respire at the 

 expense of the reserve food materials, there is a considerable 

 material loss through respiration. Thus Boussingault^ proved 

 that ungerminated seeds always have a greater dry weight than 

 seedling plants grown from them, the seedlings not having 

 developed a photosynthetic activity. For example: 



Material 



Dry wt. 

 of seeds 



Dry wt. 

 of seedlings 



Wt. lost in 

 germination 



46 wheat seeds 



I kernel of corn "geant". 

 10 pea seeds 



1.665 g. 

 0.5292 g. 

 2-237 g. 



0.712 g. 

 o. 290 g. 

 1.076 g. 



0953 g- = 57/0 

 0.2392 g. = 45% 

 1. 161 g. == 52% 



The analyses carried out by Boussingault established without 

 doubt that the loss in weight appHes only to the carbon, hydro- 

 gen and oxygen. It is now known that certain sugars form the 

 normal respiratory material. The entire respiratory process 

 can then be expressed by the equation: 



C6Hi206 + 60.2 = 6CO2 + 6H2O -f 674 Cal." 



Therefore oxygen respiration is a process antagonistic to the 

 photosynthetic building of carbohydrate. The production 

 of sugar by chloroplasts in the presence of light is expressed 

 by the equation: 



6CO2 + 6H2O + 674 Cal. = CeHi206 + 6O2. 



1 Boussingault, J. B. Agronomie, chimie agricole et physiologie 4: 245. 1868. 



'' This is 674 kg. -calories or 674,000 gram-calories. For the data in the case 

 of starch c/. Palladia's Plant Physiology (trans, by Livingston), 3rd ed., p. 223. 

 —Ed. 



