VSB OP 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 
observation; 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, 
and that as a consequence, they sometimes em ploy a phrase- 
ology calculated to mislead. When, for example, the con- 
tents 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 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 
*When these words were uttered I did not imagine that the chief 
labor of demolition would fall upon myself. 1878. 
