30 THE DATA OF BIOLOGY. 



by a special order of ethereal waves, which are absorbed in 

 producing its oscillations ; and can by its oscillations generate 

 this same order of ethereal waves. Whence it appears that 

 immense as is the difference in density between ether and 

 ponderable matter, the waves of the one can set the atoms of 

 the other in motion, when the successive impacts of the waves 

 are so timed as to correspond with the oscillations of the 

 atoms. The effects of the waves are, in such case, cumula- 

 tive ; and each atom gradually acquires a momentum made up 

 of countless infinitesimal momenta. Note further, 



that unless the members of a chemically- compound atom are 

 so bound up as to be incapable of any relative movements (a 

 supposition at variance with the conceptions of modern science) 

 we must conceive them as severally able to vibrate in unison 

 or harmony with those same classes of ethereal waves that 

 affect them in their uncombined states. While the compound 

 atom as a whole, will have some new rate of oscillation de- 

 termined by its attributes as a whole ; its components will 

 retain their original rates of oscillation, subject only to modifi- 

 cations by mutual influence. Such being the cir- 

 cumstances of the case, we may partially understand how 

 the sun's rays can effect chemical decompositions. If the 

 members of a binary atom stand so related to the undulations 

 falling on them, that one is thrown into a state of increased 

 oscillation and the other not ; it is manifest that there 

 must arise a tendency towards the dislocation of the two a 

 tendency which may or may not take effect, according to the 

 weakness or strength of their union, and according to the 

 presence or absence of collateral affinities. This inference is 

 in harmony with several significant facts. Dr Draper 

 remarks that " among metallic substances (compounds) those 

 first detected to be changed by light, such as silver, gold, 

 mercury, lead, have all high atomic weights ; and such as 

 sodium and potassium, the atomic weights of which are low, 

 appeared to be less changeable." As here interpreted, the 

 fact specified amounts to this ; that the compounds most 



