SCIENTIFIC USE OF THE IMAGINATION. 125 



other it will present itself as merely imposing a labour 

 of demolition on subsequent investigators. 1 



Let me say here that many of our physiological 

 observers appear to form a very inadequate estimate of 

 the distance which separates the microscopic from the 

 molecular limit, and that, as a consequence, they some- 

 times employ a phraseology calculated to mislead. 

 When, for example, the contents of a cell are described 

 as perfectly homogeneous or as absolutely structureless, 

 because the microscope fails to discover any structure ; 

 or when two structures are pronounced to be without 

 difference, because the microscope can discover none, 

 then, I think the microscope begins to play a mis- 

 chievous part. A little consideration will make it plain 

 that the microscope can have no voice in the question 

 of germ structure. Distilled water is more perfectly 

 homogeneous than any possible organic germ. What 

 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 ; aiid still profound and 

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

 ticles of water have been rendered diamagneticall) 

 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 



1 When these words were uttered I did not imagine that the 

 chief labour of demolition would fall upon myself. 1878. 



