310 HYDKOGEN. LBOOK n. 



paraissent, centre ? assertion d'Ingenhouz, absorber ni Fun ni 

 Fautre. II parait aussi certain, malgre Fassertion de Plenck, 

 qu'elles n'exhalent point de gas azote, sauf dans quelques cas, 

 par les corolles/ In the summer of 1844 I tested this 

 question by placing some specimens of the Conferva mucosa 

 in pump-water and in carbonated water, and allowing them 

 to act for several days on the same water, removing each day 

 the gas generated during light; the plants were therefore 

 subjected in their natural medium to different mixtures of 

 gases dissolved in the fluid. The result was, that the plants 

 in pump-water gave in six hours a gas consisting of O73, 

 N27 per cent.; in twenty-four hours, O53, N47 per cent.; 

 in forty-eight hours, O18-6, N81'4 per cent. In carbonated 

 water, in six hours, O68 per cent. ; in twenty-four hours, 

 O63 per cent. ; in forty-eight hours, O12, N88 per cent. ; 

 in seventy-two hours, O3'5, N96-5 per cent. And these 

 plants continued healthy, and acted as before when fresh 

 water was added." 



Pure hydrogen seems to act unequally upon vegetation. 

 Saussure found that a plant of Lythrum Salicaria, after five 

 weeks, had caused no alteration in a known volume of 

 hydrogen by which it was surrounded, and had not itself 

 experienced any apparent effect. Sir Humphry Davy, how- 

 ever, states that some plants will grow in an atmosphere of 

 hydrogen, while others quickly perish under such treatment. 



According to Pumas we possess decided proofs that certain 

 fungi naturally give off hydrogen. MM. Edwards and Colin 

 have shown that hydrogen is also disengaged by the stems of 

 Polygonum tinctorium when under water. It has been de- 

 monstrated by M. Payen by analysing the woody parts of 

 plants, that the hydrogen in these parts is always in slight 

 excess with respect to the oxygen. 



We must add to this the direct experiments made by 

 M. Boussingault on the development of Peas, of Clover, 

 and of Wheat. These experiments gave the following 

 results :-^ 



