36 GERMINATION OF THE SEED. CHAP. I. 



proved in the most satisfactory manner that no 

 seeds will germinate in an atmosphere of pure nitro- 

 gene or hydrogene gas ; and that the seeming ex- 

 ceptions to the rule may be all accounted for from 

 the action of the uncombined oxygene contained in 

 the water in which the seed had been placed or 

 previously steeped. For so far are seeds from ger- 

 minating in an atmosphere of nitrogene gas that, 

 even after germination has been begun and the 

 radicle developed, they will die if put into it, at 

 least unless the leaves of the plantlet have been 

 developed also. The seeds of Peas, Watercress, 

 and of Polygonum amphibium, when put into an 

 atmosphere of nitrogene gas in this state, all died 

 without any further developement of parts.* Seeds 

 immersed in water do indeed evolve a portion of 

 carbonic acid, of carburetted hydrogene, and of nitro- 

 gene. But these are elements which separate from 

 the substance of the seed during fermentation, and 

 are observed only when it is found to be in a state 

 of putrefaction. If seeds are placed in a small 

 quantity of water and confined in hydrogene gas, 

 the volume of their atmosphere is considerably 

 diminished, and the remainder is carbonic oxide. 

 But this also is the effect of putrefaction. The car- 

 bonic acid which they form of their own substance 

 is decomposed by the hydrogene with the assistance 

 of the caloric disengaged in fermentation. Water 

 is thus formed, and the carbonic acid, deprived of 

 * Saussure sur Ja Vegetation, chap. vi. sect. i. 



