USE OF THE IMAGINATION. 435 



such different antecedent states are sure to differ. In our 

 scientific judgments the law of relativity may also play 

 an important part. To two men, one educated in the 

 school of the senses, having mainly occupied himself with 

 ohservation; the other educated in the school of imagina- 

 tion as well, and exercised in the conceptions of atoms 

 and molecules to which we have so frequently referred, 

 a bit of matter, say one fifty-thousandth 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 the men these naturally appear conterminous 

 with the ultimate particles of matter; there is but a step 

 from the atom to the organism. The other discerns num- 

 berless 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 extent 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 defense and startling expansion of the doctrine 

 by Dr. Bastian will appear perfectly conclusive, to the 

 other it will present itself as merely imposing a labor of 

 demolition on subsequent investigators,* 



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, 

 jind that as a consequence, they sometimes employ a phrase- 

 ology calculated to mislead. When, for example, the con- 

 tonts of a cell are described as perfectly homogeneous or as 

 nbsolutely structureless, because the microscope fails to 

 discover any structure; or when two structures are pro- 

 nounced to be without difference, because the microscope 

 can discover none, then, I think the microscope begins to 

 play a mischievous part. A little consideration will make 

 it plain that the microscope can have no voice in the ques- 

 tion of germ structure. Distilled water is more perfectly 



* Wlien these words were uttered I did not imagine that the chief 

 labor of demolition would fall upon myself. 1878. 



