RESPIRATION AND OXYGEN. 59 



De Luca (1878 : 301) stated that fruits, flowers, and leaves in an 

 atmosphere of carbon dioxid or hydrogen, in a vacuum, or in re- 

 stricted air, gave off C0 2 , nitrogen, and, in some cases, hydrogen, 

 with the formation of alcohol and acetic acid, as a consequence of 

 the action of a ferment. 



Godlewski (1882 : 521) found that a reduced oxygen-pressure 

 exercised a definite effect upon respiration. The absorption of 

 oxygen was greatest in the case of the plants in air, and, as the 

 oxygen-content of the air was reduced, absorption decreased. The 

 reduction of the respiration intensity was due solely to reduced 

 oxygen-pressure, as the plants regained their earlier intensity when 

 the apparatus was opened, and the reduced absorption of oxygen was 

 not observed in the case of plants in pure oxygen. The intensity 

 of respiration was found to be different with the seeds of different 

 species. Under similar conditions, flaxseed respired more than those 

 of hemp and radish, and these again more than alfalfa. The respira- 

 tion energy was much less in the case of germinating starchy seeds 

 than with oily ones. Moreover, the starchy seeds differed among 

 themselves strongly in this respect; 1 gram of germinating wheat 

 grains absorbed in the same time and under similar conditions con- 

 siderably more oxygen than 1 gram of peas. Swollen peas in the 

 first stage of germination in pure oxygen absorbed considerably more 

 of this gas in the same time than in the air. Moreover, the produc- 

 tion of CO 2 in such seeds was hastened by the action of pure oxygen, 

 though in less degree. When the swelling of seeds took place with 

 the air excluded, as under water, intramolecular respiration began. 

 This did not cease immediately when the seeds were placed again 

 in the air, but was gradually replaced by normal respiration. As 

 soon as oily seeds showed rootlets, the volume of CO 2 evolved lagged 

 more and more behind that of the oxygen absorbed. In the ger- 

 mination of starchy seeds, the volume of C0 2 evolved was nearly the 

 same as that of the oxygen absorbed in all stages. The changes of 

 the pressure of the oxygen affected the respiration energy of different 

 plant parts in a very different manner. When the respiration dealt 

 with fats, the intensity depended more upon the oxygen-pressure 

 than where it took place at the expense of carbohydrates. 



In a study of intramolecular respiration, Wortmann (1882 : 520) 

 concluded that while oxygen takes a part in the formation of new 

 chemical compounds through intramolecular activity, its presence 

 has a critical effect upon the continuance of molecular change. Even 

 when plants possess the ability to exist for a time when deprived of 

 oxygen, this must be regarded not as a normal but as a pathological 

 condition, since both photosynthesis and growth are inhibited. 



Johannsen (1885 : 716) confirmed Bert's general results that the 

 physiological results of compressed air were to be ascribed to the 

 increased partial pressure of oxygen. Higher oxygen-pressures up 



