Chap, ii.] VEGETAL NUTRITION. 99 



labour of slow oxydation organised substances could not 

 accomplisb their metamorphoses, operate the exchanges of 

 matter which constitute the fundamental act of life. 



As Dutrochet said in reference to this point : " Life is one ; 

 the differences are not fundamental, and when we follow the 

 phenomena to their origin the differences disappear." ^ 



This absorption of oxygen correlative to a disengagement of 

 carbonic acid, is the act called respiratory in animals, and we 

 can give it the same name in plants, forasmuch as the essential 

 fact is identical in the two kingdoms. Animal and plant absorb 

 aiirian oxygen : animal and plant, while producing heat, 

 water, and carbonic acid, burn their fat and amylaceous matters. 

 We even find in the vegetal cells a substance analogous to the 

 principal residuum of the combustion of the albuminoids in 

 animals, urea : namely asparagine, immediate azotised and 

 crystalloidal principle. 



The respiratory property is essential to life : it is indispensable 

 even to the chlorophyllian cells, which become incapable of 

 reducing the carbonic acid when they lack oxygen, and this is 

 why they are asphyxiated in an atmosphere of pure carbonic 

 acid. 



Every living element is athirst for oxygen, and to such a 

 degree that sometimes certain organisms steal it even from 

 stable chemical compounds. 



Vibrionia,ns, studied by M. Pasteur, decompose the tartrate of 

 lime and transform lactic acid into butyric acid to procure for 

 themselves oxygen. It is besides by an analogous process that 

 in most of the vertebrates the anatomical elements deoxydise 

 the hsematoglobuline of the haematia. 



In the plant oxygen combines in totality with the carbon of 

 the tissue : for in pure oxygen there is perfect equivalence. 



Modem researches the most exact have shown that vegetal 

 growth operates only through the aid of the absorption of 

 oxygen by the tissues of plants, and that this absorption 



' Datrochet, De VEndoamoae, p. 326. 



H 2 



