SCIENTIFIC USE OF THE IMAGINATION. 127 



is it that causes the liquid to cease contracting at 39 

 Fahr., and to expand until it freezes ? We have here a 

 structural process of which the microscope can take no 

 note, nor is it likely to do so by any conceivable exten- 

 sion of its powers. Place distilled water in the field of 

 an electro-magnet, and bring a microscope to bear upon 

 it. Will any change be observed when the magnet is 

 excited ? Absolutely none ; and still profound and 

 complex changes have occurred. First of all, the par- 

 ticles of water have been rendered diamagnetically 

 polar ; and secondly, in virtue of the structure im- 

 pressed upon it by the magnetic whirl of its molecules, 

 the liquid twists a ray of light in a fashion perfectly 

 determinate both as to quantity and direction. 



Have the diamond, the amethyst, and the countless 

 other crystals formed in the laboratories of nature and 

 of man no structure ? Assuredly they have ; but what 

 can the microscope make of it ? Nothing. It cannot 

 be too distinctly borne in mind that between the micro- 

 scopic limit, and the true molecular limit, there is room 

 for infinite permutations and combinations. It is in 

 this region that the poles of the atoms are arranged, 

 that tendency is given to their powers ; so that when 

 these poles and powers have free action, proper stimulus, 

 and a suitable environment, they determine, first the 

 germ, and afterwards the complete organism. This first 

 marshalling of the atoms, on which all subsequent 

 action depends, baffles a keener power than that of the 

 microscope. When duly pondered, the complexity of the 

 problem raises the doubt, not of the power of our instru- 

 ment, for that is nil, but whether we ourselves possess 

 the intellectual elements which will ever enable us to 

 grapple with the ultimate structural energies of nature. 1 



1 'In using the expression "one sort of living substance" I must 

 guard against being supposed to mean that any kind of living 



