32 THE DATA OF BIOLOGY. 



quency with which they recur at any given point. And 

 under the influence of undulations of a certain frequency, 

 some of these atoms are transferred from atoms for which they 

 have a stronger affinity, to atoms for which they have a weaker 

 affinity. That is to say, particular orders of waves of a rela- 

 tively imponderable matter, remove particular atoms of pon- 

 derable matter from their attachments, and carry them within 

 reach of other attachments. Now the discoveries of 



Bunsen and Kirchoff respecting the absorption of particular 

 luminiferous undulations by the vapours of particular sub- 

 stances, joined with Prof. TyndalFs discoveries respecting 

 the absorption of heat by gases, show very clearly that the 

 atoms of each substance have a rate of vibration in harmony 

 with ethereal waves of a certain length, or rapidity of recur- 

 rence. Every special kind of atom can be made to oscillate 

 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 molecule 

 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 molecule as a whole will have some new rate 

 of oscillation determined by its attributes as a whole; its 

 components will retain their original rates of oscillation, sub- 

 ject only to modifications by mutual influence. Such 

 being the circumstances of the case we may partially under- 



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