428 The Physiology of Plants BOOK in 



respiration of the vegetable cell as it occurs in the sub- 

 stance of a plant. Alcohol was found in the course of 

 their experiments by Lechartier and Bellamy, and by many 

 other observers, particularly by Brefeld, De Luca, Ber- 

 thelot in 1893, Maze in 1899, and Devaux in the same 

 year. De Luca's liberated products included hydrogen and 

 marsh gas, while Boehm in 1875 observed the occurrence 

 of ammonia. 



The general occurrence of alcohol among the products ob- 

 tained under the condition of partial or complete asphyxia- 

 tion led to the opinion that intramolecular respiration is 

 identical with fermentation. Such differences as appear 

 seem to be connected with other peculiarities of the fer- 

 menting organism or cell than those connected with the 

 liberation of energy. 



The question of the relation between intramolecular or 

 anaerobic and ordinary or aerobic respiration has been 

 differently interpreted. Pfeffer pointed out the genetic 

 relationship between the two in 1878, and subsequently in 

 1885 put forward the conclusion that the withdrawal of 

 oxygen causes metabolism to assume a different character, 

 the change being gradual as the supply of the gas falls 

 off. The different character of the metabolism becomes 

 evident when we remember the different products which 

 have been found in the two cases, as has already been 

 shown. The gradual nature of the change was investigated 

 by Gerber in 1876, the material used being the fruit of the 

 Chinese date-plum (Diospyros kaki). The order of events 

 in the ripening of these fruits was found to be the follow- 

 ing. In the early stages the respiration showed that they 

 exhaled less carbon dioxide than they absorbed oxygen. The 

 pectose present in the walls of the cells was converted into 

 pectine which produced a softening of the pulp. The swelling 

 characteristic of pectine obstructed the intercellular passages 

 in the pulp, thus interfering very seriously with the trans- 



