The Minuscule Science of Antonie Van Leeuwenhoek

Leeuwenhoek wasn’t REALLY a scientist -- he had no formal training. But he made dozens of scientific discoveries. He’s credited with discovering microscopic life in a variety of forms, using lenses he ground himself.

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Episode Transcript

Speaker 1 (00:01):
Welcome to steph you missed in history Class from how
Stuff Works dot Com. Hello, and welcome to the podcast.
I'm Holly Frying and I'm Tracy V. Wilson. And the
subject of our show today is fascinating because it's Anthony
van Levin Hook and he wasn't really a scientist, but

(00:24):
he made dozens of important scientific discoveries. He is credited
with discovering microscopic life in a variety of forms. And
I just want to give a quick heads up to listeners.
This episode does discuss reproductive science. So if you listen
with younger history buffs and you maybe haven't covered that
territory yet, you might want to just give it a
quick listen before sharing. But other than that, we're just

(00:46):
going to jump right into his life because he did
some pretty impressive and also intriguing things. Yes, and we're
going to talk about what we mean by not really
a scientist later on. So, Anthony von Levin Hook was
born on October thirty two in Delft, Netherlands. This was

(01:08):
a pretty interesting year. A lot of fascinating people were
all born that same year, including John Locke, Baruch de Spinoza,
Christopher Wren, and jan Vermeer, all of them born that
same year. Yeah, it was a wild time for important people.
And his father, Phillips von Levin Hook, was a craftsman.

(01:30):
His mother, Margharita Bell van den Burch, who married Phillips
ten years before Anthony was born, was from a family
of brewers, so they were certainly a respectable family, but
they weren't really aristocratic and according to a book on
Leavin Hook and his work that was written in nineteen
thirty two by Clifford Dobell, it was tradition in their
family to alternate naming firstborn sons either Phillips or Anthony.

(01:54):
While Anthony was the first son, he was their fifth child.
We grew up with four older stars. Phillips died when
Anthony was only five years old, and a few years
after losing her first husband, Margareta remarried. This time it
was to a painter, Jacob Yon's Mulling. Margaretta and Jacob
were married in December sixteen forty and around this time

(02:15):
the young Anthony started attending school in a village in
the Netherlands called Varmond. Later, he was sent to live
with his uncle in the South Holland, province of Benthausen.
Yacob died eight years into his marriage to Margaretta, and Anthony,
who was sixteen when his stepfather passed away, was then
sent to Amsterdam. There he started learning about textiles, haberdashery

(02:39):
and linen draping through an apprenticeship, and this is likely
the point in his life where he first discovered lenses
used for magnification, because in the textile industry they were
used and sometimes still are to examine fibers and thread
counts up close. But magnification eventually, of course, took on
a far greater role in Levan Hook's life. Several years later,

(03:00):
when he was twenty, he went back home to his
hometown and he set up shop as a haberdasher. In
sixteen fifty four, Anthony married Barbara de May, a young
woman three years older than he was, who was the
daughter of one of his colleagues in the clothing trade,
and that couple had five children together, three sons and
two daughters over the course of twelve years, but four

(03:21):
of those children died quite young. Only one of their daughters,
named Maria, who was their second child, lived to adulthood.
In sixteen sixty laven Hook became the Chamberlain to the
Sheriffs of Delft, securing a regular income for this position.
He held the post for thirty nine years, and he
kept receiving income from it after he had retired, all
the way up until his death. If you're not clear

(03:44):
on what a chamberlain does, here's the description of the
job as it was laid out by his employers. There
Worships the Burgomasters and Magistrates of the Town of Delft,
has appointed and do hereby charge Anthony leven Hook to
look after the chamber, wherein the Chief Judge, the Sheriffs,
and the law officers of this town do assemble to
open and shut the foresaid chamber at both ordinary and

(04:06):
extraordinary assemblies of the foresaid gentleman, in such wise as
shall be required and needful item to show towards these gentlemen,
all respect, honor and reverence, and diligently to perform and
faithfully to execute all charges which may be laid upon him,
and to keep to himself whatever he may overhear in

(04:26):
the chamber, To clean the foresaid chamber properly, and to
keep it needed tidy, to lay the fire at such
times as it may be required, and at his own convenience,
and carefully to preserve for his own profit what coals
may remain unconsumed, and see to it that no mischance
befall thereby, nor from the light of the candles. And

(04:48):
he shall furthermore do all that is required and that
pertaineth to a good and trusty Chamberlain. So it's a
lot of words that basically sums up to keep these
offices open when we need them, comfortable, warm and lit,
and keep your mouth shut and don't burn the place
down right, which I sort of love. I also liked

(05:12):
that there's a stipulation that he can keep leftover cold
at the end of the day. Uh. But the this
stable income that he got from being chamberlain was significant
in that it meant that he could devote his free
time to science instead of having to hustle to make
ends meet, and specifically to the science of grinding lenses,
which was a hobby that leven Hook had enjoyed for

(05:33):
some time, most likely, as we said, piqued by his
work in the textile trade. It's also believed that he
had at some point seen a copy of Robert Hook's
book Micrographia, which featured illustrations and writings about Hook's work
in observational science. The lenses he was making were specifically
microscope lenses, and they weren't like modern compound microscopes. They

(05:55):
were very simple, consisting of a single lens, and leaven
Hook used them to look at all kinds of things.
While he went on to share a great many discoveries,
he did not share information about precisely how he was
making these observations. And some of his lenses were incredibly minuscule,
less than two millimeters in diameter, so tiny like I

(06:17):
would drop it on the floor and never find it again. Uh.
And of the five hundred lenses that he is estimated
to have made in his life, several samples, which were
given to the Royal Society of England after his death
at his request, could magnify anywhere from fifty to three
hundred times actual size. So they were tiny and mighty.
But even though the lenses themselves were examined by other scientists,

(06:40):
the manner in which leaven Hook used them to observe
things like fleas and bacteria still eluded them. His technique
actually remains a matter of some debate. In a moment
we will talk about the opinion of an observer who
visited leaven Hook and offered up what he thought about
all these lenses. But first we will take a moment
for a quick word from a sponsor. As we said

(07:07):
before the break, we don't know exactly how leven Hook
made all of his observations, but we're not entirely without
insight into how he worked with his lenses. In February
he was visited by Irish physician Thomas Mologna, who wrote
to the Royal Society about what he saw in the
leven Hook's lab. And he wrote this as to his

(07:28):
microscopes themselves, those which he showed me in number at
least a dozen were all of one sort, consisting only
of one small glass ground. This I mentioned because TIS
generally thought his microscopes are blown at a lamp. Those
I saw, I am sure are not placed between two
thin flat plates of brass about an inch broad and

(07:48):
an inch and a half long. In these two plates
there were two apertures, one before the other behind the glass,
which were larger or smaller as the glass was more
or less convex, or as it magnified. Just opposite to
these apertures, on one side was placed, sometimes a needle,
sometimes a slender, flat body of glass or opaque matter,

(08:09):
as the occasion required, upon which or to its apex,
he fixes whatever object he has to look upon. Then,
holding it up against the light by help of two
small screws, he places it just in the focus of
his glass, and then makes his observations. But apparently Leavin
Hook did not show him everything. This letter continues, quote,

(08:32):
such were the microscopes that I saw, And these are
they he shows to the curious that come and visit him.
But besides these, he told me he had another sort
which no man living had looked through. Setting aside himself,
these he reserves for his own private observations wholly. And
he assured me they performed far beyond any that he

(08:53):
had showed me yet, but would not allow me a
sight of them. So all I can do is barely
to believe, for I complete no experience in the matter.
So I know we read his little description, but I
want to put it in plainer language. Um, And so
you get a sense of Leavin Hook's known microscope set

(09:14):
up in more detail. It sort of resembles a small
paddle if you just look at the outline of it.
So the main body of this paddle was made up
of two identically shaped brass plates, and on each plate
there was a small hole about two thirds of the
way up the body. This is the thing that Molegna describes, uh,
these these holes having apertures, so they can be altered

(09:34):
in in terms of their size. And that lens was
placed between the two plates at that point of the hole,
so you can see through the first hole through the
lens and then through the hole on the other side.
And on the back of the paddle was this pin
that was held in place by focusing screws, and so
a specimen could be placed on that pin and then
adjusted via the focusing screws, so up or down her

(09:54):
side to side a little bit until the object of
observation came into focus through the lens. For the other
secret microscope that he showed to no one else, that
remains a mystery. Yeah, And some of his observations were
so astonishing in their detail that we know he was
using something else, we just don't know what. And even

(10:16):
as the haberdasher turned scientists, reputation grew and he was
visited by the likes of Peter the Great of Russia,
James the Second of England, and Frederick the Second of Prussia.
He would not reveal even to these monarchs his methods,
and that was something of a disappointment in some cases,
because visiting dignitaries expected that they would have this curtain
pulled back on leaven Hooks secrets, and they always had

(10:38):
to leave without such knowledge. Laven Hook's wife, Barbara, died
in sixteen sixty six, and five years later, in sixteen
seventy one, leaven Hook married again, this time to a
woman named Cornelius Swalmias. The two of them remained together
for twenty three years until she died in sixteen ninety four.
In sixteen seventy three, through a connection made by our friend,

(11:00):
Leavin Hook began corresponding with the Royal Society of England
and from that point on he corresponded with the group
about all of the various things that he saw through
his simple microscope. He made a lot of discoveries, but
he wasn't entirely methodical about the process. He didn't do
formal scientific work. Yeah, and that's really what we mean
when we talk about not a real scientist. He he

(11:23):
wasn't systematically approaching a field of study. He was just
kind of looking at stuff nat and then drawing it
or having it drawn for himself. Usually. They actually wrote
a letter to the Royal Society describing his misgivings about
sharing his findings, and in it he said quote, I
have ofttimes been besought by diverse genttleman to set down

(11:44):
on paper what I have beheld through my newly invented microscopia.
But I have generally declined, first because I have no
style or pen wherewith to express my thoughts properly, secondly
because I have not been brought up to languages or arts,
but only to buy nous, And in the third place,
because I do not gladly suffer contradiction or sensure from others.

(12:06):
This resolve of mine, however, I have now set aside
as I can't draw. I have got them drawn for me,
but the proportions have not come out as well as
I had hoped to see him, And each figure that
I send you here with was seen and drawn through
a different magnifying glass. I beg you, therefore, and those
gentlemen to whose notice these may come, please to bear

(12:26):
in mind that my observations and thoughts are the outcome
of my own unaided impulse and curiosity alone. For besides
myself in our town, there be no philosophers who practiced
this art to pray, take not amiss my poor pen
and the liberty I here take in setting down my
random notions. Yeah, he acknowledged like I'm not formally trained

(12:47):
in any of this. A lot of critiques. Also, I
can't draw, which I found really quite lovely that he
was very upfront and said, I don't like being cretic sized.
I don't really know what I'm doing, but I kind
of do want to share this stuff. As another person
who can't draw, I I empathize I'm not very good either.

(13:10):
I have a few tricks and then I'm out. But
just the same. Despite all of these sort of caveats
that he gave, the Royal Society, the Royal Society of
England welcomed his findings, and it was through the Society
that most of his work became public knowledge. They published
many of his discoveries through the years in their periodical
philosophical Transactions, and over the course of laven Hook's life,

(13:33):
three hundred seventy five different pieces of content attributed to
him appeared in philosophical transactions. Those first letters and subsequent
publications describe as mentioned in the letter we just read
from Uh. There's a later part where he talks about
them be mouths, be eyes, and the stingers of bees.
He also describes a fungus and a lout. I love

(13:56):
this part because I am very fond of insects, weird mouthparts.
You are a kindred spirit. With Antony von Levan Hook,
he wrote a lot about them. Yep. So in the
mid sixteen seventies, leaven Hook, using his microscopic limbs is
to look at water, started observing things that he referred

(14:17):
to as very little animal cules. It's possibly the most
adorable portmanteau of all time. He was looking at protozoa,
but the scientists of the sixteen seventies didn't really know
what he was seeing. They did not have a concept
to match these animal cueles. The samples that he used
for observation came from everywhere. That came from pond and rainwater,

(14:38):
from human saliva, and even from human intestines. His reputation
came under fire for all of this animal cules talk.
So when leaven Hook was describing highly magnified specimens of
known things like insects and fungus. His work was accepted
by the Royal Society and even lauded, But then talking
about microscopic living things was an their matter entirely. It

(15:01):
sounded completely preposterous to a lot of people at the time.
It was such a sea change in the scientific world
that a number of members of the Royal Society dismissed
the work outright. Eventually, the year after publication, and after
several people had observed Leavin Hook's work and yet others
had managed to duplicate his findings, his discovery was actually recognized.

(15:24):
Next up, we will talk about an area of discovery
that leaven Hook was initially reluctant to even consider. But
first we will take another quick sponsor break. In sixteen
seventy seven, Anthony van leven Hook began studying supurbon a
zoa from a variety of species. Other scientists had already

(15:47):
encouraged him to turn his microscope to the examination of semen,
but he had been really pretty apprehensive because he thought
writing about such things might be perceived as crude and impolite. Finally, though,
and Hook found the courage to do some observational work
in this area. When he finally wrote to the Royal
Society about what he had seen through his lenses, the

(16:08):
letter was awkward and nervous, and it left the matter
of what to do with this information up to the recipient.
He wrote, quote, what I investigate is only what, without
sinfully defiling myself, remains as a residue after conjugal coitus.
And if your Lordship should consider that these observations may
discussed or scandalized the learned, I earnestly beg your Lordship

(16:32):
to regard them as private, and to publish or destroy
them as your Lordship thinks fit so nervous so, this
entire branch of science at the time was loaded with
varying ideas and concepts to explain exactly how reproduction played out.
There were theories that some sort of vapor was involved

(16:55):
in male ejaculate that catalyzed the production of new life
on the part of women in and another idea was
that all the material to make a new human was
contained in the sperm and that it merely needed to
be implanted in a uterus for gestation. And all of
these varying theories, there were many others were categorized into
two basic schools of thought, epigenesists, who believed that some

(17:17):
sort of combining of materials from a man and a
woman created life, and preformationists, who thought that the complete
makeup of a human was contained in one or the other,
the sperm or the egg, and that sexual intercourse served
as some sort of catalyst for the process of development.
Laven Hook's work in this area was really controversial. I
mean it should be obvious from what he felt compelled

(17:40):
to point out about it in that letter that he wrote.
There were some members of the Royal Society who thought
he had actually misidentified parasites, and there was a lot
of stigma around this kind of research once he had started,
though he continued on with it, eventually examining spermatozoa from
lots of other animals, mostly mammals, but also birds, fish, mollusks,

(18:02):
and amphibians. Yeah, he did a lot of like frog research,
but spermonozo is certainly not the only thing. But leaven
Hook on the scientific map. We talked about some of
his insect observations earlier, but he noted, for example, parthenogenesis
in aphids, and he studied and described like we mentioned
the tiniest parts of insects and plants, and offered insights

(18:25):
that previously had not been known into both of those.
In sixteen eighty he made observations that significantly advanced human
knowledge of yeast, and his work really led to great
strides in the understanding of plant life and how it grows.
He also described red blood cells for the first time
known about in human history in sixteen eighty, and he

(18:47):
was elected a Fellow of the Royal Society of England
that year. In sixteen eighty three, Philosophical Transactions published a
drawing by leaven Hook that's believed to be the first
graphical depiction of bacteria. He made this discovery while looking
at examples of plaque from the mouths of himself and
several other people. Quote. I then most always saw with

(19:08):
great wonder that in said matter there were many very
little living animal cules, very prettily a moving. That's a
nice way to describe bacteria in your mouth. Oh they're
so cute, They're just pretty. One of the most important
contributions made to science by leaven Hook was the work
he did to disprove the concept of spontaneous generation. So

(19:32):
just in case you need a refresher on that one.
Spontaneous generation was a theory that life forms could generate
spontaneously from non living matter. The common example is the
once widely believed idea that mag gets spontaneously generated from
rotting meat. I had a book as a child that
included the example of barnacles that looked like geese becoming geese,

(19:57):
and I was at the age of five, like, are
you kidding me? That's fantastic. I wish I still had
that book somewhere. It was bizarre. So Leban Hook and
his study of little tiny organisms started examining the life
cycles of small creatures and studying weevils, he observed that

(20:17):
they were grubs that hatched from eggs and not as
was commonly accepted, just sprouting forth from wheat. Similarly, his
examination of fleas resulted in a detailed description of their
life cycle, including hatching from eggs, which was in opposition
to a popular belief that they were generated spontaneously from sand,

(20:38):
dust or other particulate non living matter. For a long time,
what we now know our aunt's pupae were believed to
be their eggs, and it was Leaven Hook who set
the record straight on that, establishing that their eggs are
in fact much tinier than that, and that the insects
passed through a larval stage before the pupil was formed.

(20:58):
His observations were not exclude sibly focused on tiny creatures,
though he also studied sea creatures such as muscles and eels,
both of which had been at one point believed to
be the product of spontaneous generation, and seventeen o two
he wrote extensively on the microscopic aquatic invertebrates known as rotifers.
So while the subjects of his work were at times

(21:21):
quite small, these were really huge developments in the scientific community.
He died where he was born, on the of August
seventeen twenty three. And we're going to revisit that letter
that Thomas Molna wrote to the Royal Society while visiting
laban Hook, because in addition to the sections that we
read earlier in the show, he also included this description,

(21:43):
which became a little bit famous. I found him a
very civil, complacent man, and doubtless of great natural abilities,
but contrary to my expectations, quite a stranger to letters master,
neither of Latin, French or English or any of the
modern tongue besides his own, which is a great hindrance
to him and his reasonings upon his observations. For being

(22:06):
ignorant of all other men's thoughts, he is wholly trusting
to his own, which I observed now, and then lead
him into extravagances and suggest very odd accounts of things. Nay,
sometimes such as are wholly irreconcilable with all truth. You see, sir,
how freely I give you my thoughts on him because
you desired it. But in some ways it seems as

(22:28):
though part of the reason that Antony von Levin Hook
was so prolific in his observations was because he was
an outsider, without pre existing scientific ideas informing his work.
He just saw what he saw and then he recorded it,
and he didn't feel constrained by what was expected of
a scientist. Yeah, even though Leavin Hook made his observations

(22:50):
beginning in sixteen seventy three, it wasn't even until the
eighteen hundreds that people started to comprehend that, for example,
the bacteria that he described were linked to disease. So
he was so far ahead that science could not had
to have a little time to catch up. To what
he had discovered, and while his letters to colleagues and
to the Royal Society were collected into books, he never

(23:13):
formally penned a book or wrote a scientific paper. In
an interview with the Smithsonian in Marvin Bolt, who was
curator of Science and Technology at the Corning Museum of Glass,
which is a fascinating place if you ever get the
opportunity to go there. Quote Robert Hook was looking at
parts of animals that were already known. Then Von Levin

(23:33):
Hook went deeper to see on a cellular level things
no one had ever seen before, such as muscle fibers, sperm,
and bacteria. He really blazed the trail. So that's Anthony
von Levin Hook and his teeny tiny science. I love
I love it so much. Do you have teeny tiny
listener mail? It is kind of teeny tiny listener mail. Uh.

(23:55):
It is from our listener Maureen, who says, Hi, Holly
and Tracy. In September I went to London and visited
the Museum of London, which is absolutely awesome. You start
out in prehistory and make your way through London as
it was right up to the present day. I recommend
it to everyone and closed is a doll or ornament
of Ann Fanshawe, whose father had been the Mayor of London.
She's in her court dress, which is housed at the

(24:17):
Museum of London, and it is frankly bananas. I couldn't
imagine wearing a skirt that big or elaborately embroidered. Knowing
your love of historical fashion, I had to get the
doll for you. I love the show and listen religiously.
I've learned so much interesting things that even sometimes helped
me at work. I am a public librarian. Thanks for everything, Okay,
Maureen one, thank you for being a librarian, especially a

(24:38):
public librarian. Those are vital roles. And to thank you
for this adorable um ornament, I'm gonna say it's an ornament.
She's lovely, trying to show her to Tracy. She's so pretty.
So I can't tell you how much I appreciate your thoughtfulness. Uh.
It's just the most darling thing and I will treasure it. Uh.
If you would like to write to us, you can

(24:59):
do so and his street podcast at house works dot com.
You can also find us across the spectrum of social
media as Missed in History kind of visit us at
our website missed in history dot com, where you'll find
every episode of the show that's ever existed, including uh
some reference notes of any of the shows that Tracy
and I have worked on. And you can also just
you know, root around in history and find out what

(25:20):
we've been talking about all these years. So we welcome
you at missed in history dot com. For more on
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