24 Mr. J. Croll on What determines Molecular Motion ? 



Molecular physics has made great advance of late years ; but it 

 has not made much advance in that particular direction which 

 can be of service in explaining how molecular motion in organic 

 nature is determined. It is thought, however, by the advocates 

 of the physical school that although at present we are unable to 

 explain how organic nature can be built up by the play of the 

 ordinary chemical and physical forces, yet at some future day, 

 when we shall have come to know far more of molecular physics 

 than we do at present, then we may be able to explain the mys- 

 tery. This is the cherished hope of modern Evolutionists, and 

 of the advocates of the physical theory of life. But it is a mental 

 delusion, a dream which will never be realized. A little consi- 

 deration might satisfy any one that Chemistry and Physics will 

 never explain the mystery of nature. 



The terms Light, Heat, Electricity, Magnetism, &c. are different 

 names which we apply to different modes of molecular motion ; 

 and it is true that at present little is known regarding the 

 nature of these modes of motion ; but notwithstaading this we 

 have reason to conclude that, although we knew all that abso- 

 lutely can be known regarding them, yet it would not afford us 

 any explanation of the cause of the determination of molecular 

 motion in organic nature. 



The character of a cause may often to some extent be judged 

 indirectly from the nature of the effects produced. It is from 

 the effects produced that we know, for example, that that mode 

 of molecular motion called Heat differs from that mode called 

 Electricity. The effects do not as yet enable us to determine 

 wherein this difference consists ; but it enables us to conclude 

 with certainty that there is a difference. Effects which are elec- 

 trical we refer to that unknown mode of motion called Electri- 

 city. We do not refer them to that mode called Heat, because 

 the effects are different from those which we ascribe to Heat. 

 Each mode of motion, each energy is distinguished by the effects 

 which it produces. Determination of the molecules cf matter 

 according to the objective idea of a plant or an animal, is an 

 effect which is constantly taking place in organic nature. To 

 attribute this effect to Electricity, for example, would be far 

 more absurd than to attribute electrical effects to gravitation or 

 to heat ; for the difference between this effect and any electrical 

 effect is immeasurably greater than between electrical effect 

 and any effects produced by heat or by gravitation or any 

 other of the forces of inorganic nature. It would be far more 

 rational to attribute all the phenomena of the inorganic world, 

 say, to heat, than to attribute the determination of molecular 

 motion in the organic world to chemical and physical energies. 



It must now be obvious that nothing which can be deter- 



