338 MEMORIAL OF JOSEPH HENRY. 



into the structure of the organism. "■ All the material of which a 

 tree is built up, (with the exception of that comparatively small 

 portion which remains after it has been burnt, and constitutes the 

 ash,) is derived from the atmospliere. In the decomposition of the 

 carbonic acid by the chemical ray, a definite amount of power is 

 expended, and this remains as it were locked up in the plant so long 

 as it continues to grow." And tlius under the expenditure of an 

 external force, the plant (Avhether the annual cellular herb or the 

 perennial fibrous tree) was shown to be built up from the simpler 

 stable binary compounds of the inorganic world to the more com- 

 plex and unstable ternary compounds of the vegetable world. " In 

 the germination of the plant, a part of the organized molecules 

 runs down into carbonic acid to furnish power for the new arrange- 

 ment of the other portion. In this process no extraneous force is 

 required: the seed contains within itself the power, and the 

 material, for the growth of the new plant up to a certain stage 

 of its development. Germination can therefore be carried on 

 in the dark, and indeed the chemical ray which accompanies light 

 retards rather than accelerates the process." This important 

 organic principle appears to receive in these passages its earliest 

 enunciation. 



It was also pointed out that on the completion of the cycle of 

 growth (however brief or however extended), the decay of the 

 plant not only returns the elevated matter to its original lower 

 plane, but equally returns the entire amount of heat energy 

 absorbed in its elevation : an amount precisely the same, whether 

 the slow oxidation be continued through a series of years, or a 

 rapid combustion be completed in as many minutes. "The poAver 

 wliicli is given out in the whole descent is according to the dynamic 

 theory, just equivalent to the power expended by the impulse from 

 the siin in elevating the atoms to the unstable condition of the 

 organic molecules. If this power is given out in the form of 

 vibrations of the jethcrial medium constituting heat, it will not be 

 appreciable in the ordinary decay say of a tree, extending as it may 

 tlirough several years: but if the process be rapid, as in case of 

 combustion of wood, then the same amount of power will be given 

 out in the energetic form of heat of high intensity, 



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