20 Mr. J. Croll on What determines Molecular Motion ? — 



is not an object in nature that does not stand in the relation- 

 ship of a means to something as an end. And there exists a unity 

 in the ends as well as in the forms. All molecular motions must 

 consequently have this double relationship of plan and purpose. 

 How, then, is all this order and unity both of plan and purpose 

 in molecular motions to be accounted for ? 



Molecular Motion in relation to unity of plan. 



I shall now consider the explanation of molecular motion in 

 regard to the Form of objects. The consideration of molecular 

 motion in relation of Means to Ends must be deferred till a 

 future occasion. 



The objects of nature, as we have seen, are built up molecule 

 by molecule, and are thus the products of molecular motion. 

 Energy is that which moves or transports the molecules in the 

 building-up process; but it is not the mere transport of the mo- 

 lecules, as has been repeatedly shown, which gives to the object 

 produced its form. The form assumed is due, not to the motion 

 of the molecules, but to the determination of that motion — to 

 the way in which the motions are guided and adjusted in rela- 

 tion to one another. It is not the energy which conveys the 

 bricks that accounts for the form of the house, but that which 

 guides and directs the energy. So far as the form of the house 

 is concerned, it is a matter of indifference whether the bricks 

 are conveyed on the backs of labourers or transported by a steam- 

 crane. In like manner, in accounting for organic forms, we 

 must exhibit not the mere energy which moves the molecules, 

 but that which directs and guides the energy. 



But it has been already proved that energy cannot be deter- 

 mined by energy; consequently that which determines energy 

 is not itself an energy. Therefore the thing which we are in 

 search of, which accounts for the order and arran2;ement pre- 

 vailing in the molecular movements in nature, is a something 

 not of the nature of a force or an energy. 



The question now to be considered is, Can this marvellous 

 adjustment of molecular motions be explained by any thing 

 which is found within the domains of chemistry and physics ? 

 The advocates of the physical theory must afford us some expla- 

 nation of the cause of the determination of molecular motion 

 derived from physics and chemistry, if their theory in reality rests 

 upon a true foundation. 



The chief argument in favour of this theory seems to be the 

 one to which allusion has already been made, viz. that all the 

 energies in nature to which the term " vital '^ has been applied 

 evidently have a chemical or a physical origin. For example, 

 the vital energies of our bodies are derived from the food we eat, 

 the water we drink, and the air we breathe ; they therefore ex- 



