126 FRAGMENTS OF SCIENCE. 



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

 ottrer large. So, also, as regards the appreciation ot 

 the most minute foims of life revealed by the micro- 

 scope. To one of the men these naturally appear con- 

 terminous with the ultimate particles of matter ; there 

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

 other discerns numberless organic gradations between 

 both. Compared with his atoms, the smallest vibrios 

 and bacteria of the microscopic field are as behemoth 

 and leviathan. The law of relativity may to some ex- 

 tent explain the different attitudes of two such persons 

 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 by 

 Dr. Bastian will appear perfectly conclusive, to the 

 other it will present itself as merely imposing a labour 

 of demolition on subsequent investigators. l 



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 



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

 chief labour of demolition would fall upon myself. 1878. 



