doctrine of spontaneous generation; but the fact is, and you will see it
if you will take the trouble to look into his works, Harvey believed it
as profoundly as any man of his time; but he happened to enunciate a
very curious proposition--that every living thing came from an 'egg';
he did not mean to use the word in the sense in which we now employ it,
he only meant to say that every living thing originated in a little
rounded particle of organized substance; and it is from this
circumstance, probably, that the notion of Harvey having opposed the
doctrine originated. Then came Redi, and he proceeded to upset the
doctrine in a very simple manner. He merely covered the piece of meat
with some very fine gauze, and then he exposed it to the same
conditions. The result of this was that no grubs or insects were
produced; he proved that the grubs originated from the insects who came
and deposited their eggs in the meat, and that they were hatched by the
heat of the sun. By this kind of inquiry he thoroughly upset the
doctrine of spontaneous generation, for his time at least.

Then came the discovery and application of the microscope to scientific
inquiries, which showed to naturalists that besides the organisms which
they already knew as living beings and plants, there were an immense
number of minute things which could be obtained apparently almost at
will from decaying vegetable and animal forms. Thus, if you took some
ordinary black pepper or some hay, and steeped it in water, you would
find in the course of a few days that the water had become impregnated
with an immense number of animalcules swimming about in all
directions. From facts of this kind naturalists were led to revive the
theory of spontaneous generation. They were headed here by an English
naturalist,--Needham,--and afterwards in France by the learned Buffon.
They said that these things were absolutely begotten in the water of
the decaying substances out of which the infusion was made. It did not