60 The Chemical Statics of Organised Beings. 



Ashes. — An immense quantity of water passes through the 

 vegetable during the period of its existence. This water 

 evaporates at the surface of the leaves, and necessarily leaves, as 

 residue, in the plant the salts which it contained in solution. 

 These salts compose the ashes, products evidently borrowed 

 from the earth, to which, after their death, vegetables give it 

 back again. 



As to the form in which these mineral products deposit them- 

 selves in the vegetable tissue, nothing can be more variable. 

 We may remark, however, that among the products of this na- 

 ture, one of the most frequent and most abundant is that pecti- 

 nate of lime discovered by M. Jacquelain in the ligneous tissue 

 of most plants. 



IV. If, in the dark, plants act as simple filters which water 

 and gases pass through ; if, under the influence of solar light, 

 they act as reducing apparatus which decompose water, car- 

 bonic acid, and oxide of ammonium, there are certain epochs and 

 certain organs in which the plant assumes another, and altogether 

 opposite, part. 



Thus, if an embryo is to be made to germinate, a bud to be 

 unfolded, a flower to be fecundated, the plant which absorbed 

 the solar heat, which decomposed carbonic acid and water, all 

 at once changes its course. It burns carbon and hydrogen ; it 

 produces heat, that is to say, it takes to itself the principal cha- 

 racters of animal life. 



But here a remarkable circumstance reveals itself. If barley 

 or wheat is made to germinate, much heat, carbonic acid, and 

 water are produced. The starch of these grains first changes 

 into gum, then into sugar, then it disappears in producing car- 

 bonic acid, which the germ is to assimilate. Does a potato 

 germinate, here, also, it is starch which changes into dextrine, 

 then into sugar, and which at last produces carbonic acid and 

 heat. Sugar, therefore, seems the agent by means of which 

 plants develope heat as they need it. 



How is it possible not to be struck from this with the coinci- 

 dence of the following facts? Fecundation is always accom- 

 panied by heat. Flowers as they breathe produce carbonic acid : 

 they therefore consume carbon ; and if we ask whence this 

 carbon comes, we see, in the sugar cane, for example, that the 

 sugar accumulated in the stalk has entirely disappeared when 

 the flowering and fructification are accomplished. In the beet 

 root, the sugar continues increasing in the roots until it flowers ; 

 the seed-bearing beet contains no trace of sugar in its root. In 

 the parsnep, the turnip, and the carrot, the same phenomena 

 take place. 



Thus, at certain epochs, in certain organs, the plant turns into 



