415 



frequently referred, a bit of matter, say ^-injirotli of an inch 

 in diameter, will present itself differently. The one descends 

 to it from his molar heights, the other climbs to it from his 

 molecular lowlands. To the one it appears small, to the 

 other large. So also as regards the appreciation of the most 

 minute forms of life revealed by the microscope. To one of 

 these men they naturally appear conterminous with the 

 ultimate particles of matter, and he readily figures the 

 molecules from which they du*ectly spring ; with him there 

 is but a step from the atom to the organism. The other 

 discerns numberless organic gradations between both. Cora- 

 pared with his atoms, the smallest vibrios and bacteria of the 

 microscopic field are as behemoth and leviathan. The law 

 of relativity may to some extent explain the diff"erent attitudes 

 of these two men with regard to the question of spontaneous 

 generation. An amount of evidence which satisfies the one 

 entirely fails to satisfy the other ; and while to the one the 

 last bold defence and startling expansion of the doctrine will 

 aj^pear perfectly conclusive, to the other it will present itself 

 as imposing a profitless labour of demolition on subsequent 

 investigators. The proper and possible attitude of these two 

 men is that each of them should work as if it were his aim 

 and object to establish the view entertained by the other. 



1 trust, Mr. President, that you — whom untoward circum- 

 stances have made a biologist, but Avho still keep alive your 

 sympathy with that class of inquiries which nature intended 

 you to pursue and adorn — will excuse me to your brethren if 

 I say that some of them seem to form an inadequate estimate 

 of the distance which separates the microscopic from the mo- 

 lecular limit, and that, as a consequence, they sometimes 

 employ a phraseology which is calculated to mislead. When, 

 for example, the contents of a cell are described as perfectly 

 homogeneous, as absolutely structureless, because the micro- 

 scope fails to distinguish any structure, then I think the 

 microscope begins to play a mischievous part. A little con- 

 sideration will make it plain to all of you that the microscope 

 can have no voice in the real question of germ structure. 

 Distilled water is more perfectly homogeneous than the con- 

 tents of any possible organic germ. What causes the liquid 

 to cease contracting at 39° Fahr., and to grow bigger until it 

 freezes ? It is a structural process of which the microscope 

 can take no note, nor is it likely to do so by any conceivable 

 extension of its powers. Place this 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 



