oot upon the bottom round of the
ladder. Truly he would be a bold man who would venture to predict where
she will be fifty years hence.

There is another inquiry which bears indirectly upon this question,
and upon which I must say a few words. You are all of you aware of the
phenomena of what is called spontaneous generation. Our forefathers,
down to the seventeenth century, or thereabouts, all imagined, in
perfectly good faith, that certain vegetable and animal forms gave
birth, in the process of their decomposition, to insect life. Thus,
if you put a piece of meat in the sun, and allowed it to putrefy, they
conceived that the grubs which soon began to appear were the result
of the action of a power of spontaneous generation which the meat
contained. And they could give you receipts for making various animal
and vegetable preparations which would produce particular kinds of
animals. A very distinguished Italian naturalist, named Redi, took up
the question, at a time when everybody believed in it; among others our
own great Harvey, the discoverer of the circulation of the blood. You
will constantly find his name quoted, however, as an opponent of the
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 i