FUNCTION.] PHENOMENA OF GERMINATION. 261 



renders it scarcely soluble in water. To enable the parts 

 to be sufficiently moistened, it is therefore necessary that the 

 seed should be decarbonised by oxygen. This explains why 

 Peas scarcely ripe will germinate much more rapidly than 

 those which are fully matured ; the former contain more pure 

 water and less carbon. In fact, the effect of the abstraction, 

 by oxygen, of the fixed carbon, is, to bring back the seed to 

 the state in which it was, before it was provided with the 

 means of remaining unchanged in a torpid state. The sweet 

 taste of germinating barley is, in reality, what the seeds 

 possessed before they were finally hardened. The destruction 

 of oxygen, by the carbon of the seed, produces a sensible 

 heat in germinatioli, just as a similar cause produces a similar 

 effect in flowers, when the fsecula of their disc is converted 

 into sugar (see p. 211). Hence the heat of masses of Barley 

 which are made to germinate in darkness in order to become 

 malt : and it can scarcely be doubted, that the change of the 

 starch of that grain into sugar is chemically owing to the 

 abstraction of a proportion of its carbon, and the addition of 

 some other proportion of oxygen. 



It has been asked, Whence comes the oxygen which, com- 

 bining with the carbon of the seed, forms the carbonic acid 

 expelled in germination ? The usual answer is, From the 

 air : and it is necessary that seeds should have access to the 

 atmosphere in order to germinate. But Messrs. Edwards 

 and Colin have shown, by recent experiments, that the oxygen 

 of which germinating seeds make use is obtained by the 

 decomposition of water, and not necessarily from the air. 

 These physiologists placed Beans in water, under such circum- 

 stances that they were completely cut off from access to the 

 air. The Beans disengaged bubbles of air from their sides in 

 great abundance for the space of four days, a part of such air 

 collecting in a receiver, but the greater part dissolving in the 

 water. This air consisted chiefly of carbonic acid; there 

 was also a trace of oxygen, and a small quantity of what 

 appeared to be nitrogen. The hydrogen left after the decom- 

 position of the water appeared to be absorbed by the seed, 

 either wholly or in great part. This proof of the decomposi- 

 tion of water by the vital energies of the seed is justly stated, 



