Flea Glass Apt Name for a Microscope
An unknown entomologist once stated that insects are big enough to see,
but not big enough to see well. That comment speaks volumes about human-insect
interaction. When it comes to insects, what we can't see, we imagine!
The human imagination sometimes runs wild when it comes to insects. Take
for instance, that human psychological condition known as delusory parasitosis.
People suffering from this disorder believe they have microscopic creatures
living on them. But they don't; they just imagine that they do. It has
to do with the small size of insects, such as fleas and lice.
That brings us to the development of the microscope and how that device
showed insects in a new light. Galileo is known for his work with the
telescope, but when he looked through the other end of the device he had
a microscope. While he was not a biologist, the earliest biological observation
with a microscope is credited to Galileo. He is said to have reported
that each eye of a small animal is "perforated with holes to afford
passage to the images of visible things." Galileo was describing
the compound eye of an insect.
The earliest published figures prepared with the aid of a microscope
are credited to Francesco Stelluti, who in 1630 wrote, "I have used
the microscope to examine bees and all their parts."
Stelluti also noted, maybe bragged is a more appropriate term, that he
had prepared figures of other insects that were unknown to Aristotle!
Aristotle, maybe the greatest biologist who ever lived, didn't have the
use of the microscope. So, he can be excused for overlooking a few small
In the early days of its use, the microscope was called a flea glass
-- a descriptive term, for sure. The name probably originated from the
work of the classical microscopists, including Antony van Leeuwenhoek.
In 1693, Leeuwenhoek described the metamorphosis of the flea. He drew
detailed pictures of egg, larvae, pupa and adult. He even described a
minute mite parasite on the larva. This observation probably gave rise
to the Johathan Swift lines:
"So naturalists observe, a flea
Has smaller fleas that on him prey;
And these have smaller still to bite 'em;
And so proceed ad infinitum."
Another microscopist, Robert Hooke, also looked at minute insects, spiders
and mites. He drew the flea in great detail and large size. His pictures
were unsurpassed for accuracy for nearly a century.
The flea glasses of more than 300 years ago allowed observers to look
at insects more closely than ever before. The new-found tool allowed those
who took an up close and personal look at insects to discover all kinds
of things. For instance, some aphids, when dissected, had little aphids
inside, supporting the idea that aphids sometimes gave birth to live young.
The insides of insects were no longer secret, and the early scientists
had their first close up look at the internal workings of insects. It
was discovered that the holes on the sides of insects were attached to
tubes, forming the breathing system.
The microscope has allowed scientists to clearly look at very small insects.
But some people prefer not to see the teeth on a flea. They would just
as soon not know that much about something that will take a bite when
it gets the chance.