120 WRITINGS OP JOSEPH HENRY. [1855- 



The energy of the solar vibrations communicated to the ice 

 modifies its cohesion, converting it into the liquid state, 

 and the ice again becoming solid gives out the same amount 

 of heat in a less energetic form. Even the motive power of 

 the wind is expended by the friction of its particles in pro- 

 ducing a portion of the heat which gave rise to its motion, 

 and this also is radiated into celestial space. 



But the most interesting part of our inquiry relates to 

 the effects which the radiation alone of heat from the sun 

 would have on the vegetable germs buried in the soil. If 

 these germs were enclosed in sacs filled with starch and other 

 organic ingredients, stored away for the future use of the 

 young plant, as in the case of the tuber of the potato, or the 

 fleshy part of the bean, as soon as the sun penetrated beneath 

 the surface in suflScient degree to give mobility to the com- 

 plex organic molecules of which these materials consist, (the 

 proper degree of moisture also supposed to be present,) ger- 

 mination would commence. The young plant would begin 

 to be developed, would strike a rootlet downward into the 

 earth, and elevate a stem towards the surface furnished with 

 incipient leaves. The growth would continue until all the 

 organic matter in the tuber or sac was exhausted; the fur- 

 ther development of the plant would then cease, and in a 

 short time decay would commence. 



But let us dwell a few minutes longer on the condition of 

 the plant and the tuber before the downward action becomes 

 the subject of consideration. If we examine the condition of 

 the potato which was buried in the earth, we shall find re- 

 maining of it nothing but the skin, which will probably con- 

 tain a portion of water. What has become of the starch and 

 other matter which originally filled this large sac? If we 

 examine the soil which surrounded the potato, we do not 

 find that the starch has been absorbed by it ; and the answer 

 which will therefore naturally be suggested is, that it has 

 been transformed unto the material of the new plant, and it 

 was for this purpose originally stored away. But this, 

 though in part correct, is not the whole truth ; for if we 

 weigh a potato prior to germination, and weigh the young 



