RESPIRATION. 105 



operations. It is often said that plants cannot be sustained 

 on organic nutriment, that they live on inorganic matter, 

 which they organize as food for animals ; but we apprehend 

 parasitic plants must be regarded as exceptional cases; 

 for these derive their nutriment from the elaborated juices 

 of the plants on which they are found, and not at all from 

 the earth and atmosphere, the usual sources of vegetable 

 nutrition. These plants contaminate the air like animals, 

 absorbing its oxygen and giving out carbonic acid. This 

 fact is so well known and established that it will not be 

 disputed. It is sufficient, therefore, if we refer to the ex- 

 periments of M. Lory upon the respiration of the Oro- 

 banchaceffi.* 



Oxygen is absorbed and carbonic acid evolved in ger- 

 mination, at the birth of the young plant, and in flower- 

 ing, when it arrives at an adult state. In both in- 

 stances, starch is oxydized and converted first into dextrine 

 and then into sugar, for the nutriment of the young em- 

 bryo, stamens, and pistils, and these processes are accom- 

 panied with a development of heat. Both the embryo and 

 the flower, physiologically considered, may be regarded as 

 exercising a parasitic action on the organic matter pre- 

 viously elaborated for them. The respiration of the coty- 

 ledonary leaves of the embryo, and of the coroUine envelope 

 of the stamens and pistils is, in every respect, a true oxyda- 

 tion or combustion of the store of saccharine matter, accom- 

 panied by the evolution of carbonic acid. 



It is true that plants, with the exception of such as are 

 parasitic, live on mineral matter, which they conv^t into 

 organized products; but the organic matter which they 

 thus create is not available for the development either of 



* "Annales des Scienoea-NaturBlles." Botanique, Sept. 1847. 



