t 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 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. [Footnote: When
these words were uttered I did not imagine that the chief labour of
demolition would fall upon myself. 1878.]

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 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 mischievous 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 degrees 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 extension 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; and still profound and complex changes have occurred. First of
all, the particles of water have been rendered diamagnetically polar;
and secondly, in virtue of the structure impressed 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 of man no structure?
Assuredly they have; but what can the microscope make of it? Nothing.
It cannot be too distinctl