Life and Writings of Theodore de Sausmre. 17 



in the absorbing organ. The flowers presented this pecu- 

 liarity, that they replace, by the disengagement of an equal 

 quantity of azote gas, the proportion of oxygen absorbed. 



After these fundamental results, Theodore de Saussure 

 examined the influence of oxygen gas on vegetables which 

 are dead, or in a state of fermentation. He found that, at 

 first, this gas does not become fixed in their tissue, nor com- 

 bine with their hydrogen, but only carries off" a portion of 

 their carbon. This eff'ect takes place in acetification, in the 

 precipitation of extracts, in the coagulation of vegetable albu- 

 men, &c. The oils alone are an exception. At the same 

 time, a portion of the elementary water is withdrawn from the 

 vegetable. When the fermentation augments, the proportion 

 of disengaged water increases, and the oxygen absorbed, not 

 being found entirely in the acid produced, probably combines 

 with the hydrogen to form this combination. 



Theodore de Saussure afterwards devoted himself to the 

 detailed analysis of soil, the influence of which has been a 

 point so much controverted by the physiologists of our day, 

 and he ascertained that it contains more carbon than the 

 plants from which it proceeds. Oxygen penetrates into this 

 soil, to carry off^ its carbon, to convert it into carbonic acid, 

 and thus make it contribute to the sustenance of vegetables. 

 As the rest of the soil is soluble in water, the author thence 

 concluded that it may be entirely destructible at the atmo- 

 spheric temperature, by the united action of air and rain, and 

 that that circumstance explains its small accumulation even in 

 places where vegetation has been longest established. 



Continuing his researches on the vegetation of plants, the 

 author shews that they can live in media deprived of oxygen 

 gas, only because their green parts exhale this gas by the de- 

 composition of carbonic acid ; and, in fact, when we absorb, 

 by degrees, the exhaled oxygen, we put a stop to the develop- 

 ment of the plant. Vegetables absorb neither azote, nor 

 hydrogen, nor carbonic oxide gas ; they live in these as in 

 a vacuum, by means of the oxygen exhaled by their leaves. 

 We must only avoid, in this latter case, the too direct action 

 of the sun's rays. 



The second important point which presented itself for exa- 



VOL. XL. NO. LXXIX. — JAN. 1846. B 



