van Leeuwenhoek Antony  (October 24, 1632 - August 30, 1723), full
name Thonius Philips van Leeuwenhoek (pronounced 'vahn Laywenhook')
was a Dutch tradesman and scientist from Delft, Netherlands. He is commonly
known as "the Father of Microbiology". Born the son of a basket
maker, at age 16 he secured an apprenticeship with a Scottish cloth
merchant in Amsterdam. He is best known for his work on the improvement
of the microscope and for his contributions towards the establishment
of microbiology. Using his handcrafted microscopes he was the first
to observe and describe single celled organisms, which he originally
referred to as animalcules, and which we now refer to as microorganisms.
He was also the first to record microscopic observations of muscle fibers,
bacteria, spermatozoa and blood flow in capillaries (small blood vessels).
During his lifetime
van Leeuwenhoek ground over 500 optical lenses. He also created over
400 different types of microscopes, only nine of which still exist today.
His microscopes were made of silver or copper metal frames holding hand-ground
lenses. Those that have survived the years are able to magnify up to
275 times. It is suspected, though, that van Leeuwenhoek possessed some
microscopes that could magnify up to 500 times. Although he has been
widely regarded as a dilettante or amateur, his scientific research
was of remarkably high quality.
with the microscope
In 1648 in Amsterdam van Leeuwenhoek saw his first simple microscope,
a magnifying glass mounted on a small stand used by textile merchants
capable of magnifying to a power of 3. He soon acquired one for his
own use. In 1654, he left Amsterdam, moved back to Delft and started
his own lucrative drapery business there. In 1660, he was appointed
chamberlain of the Lord Regents of Delft. It is believed that soon after
1665 he read a book by Robert Hooke, titled Micrographia. His reading
of Hooke's book is believed to have roused an interest in van Leeuwenhoek
to use his microscopes for the purpose of investigating the natural
world beyond the mere quality of the fabrics he sold. In 1669 he obtained
a degree in geography, leading to his later appointment as geographer
in microscopes and a familiarity with glass processing led to one of
the most significant, and simultaneously well-hidden, technical insights
in the history of science. By placing the middle of a small rod of lime
glass in a hot flame, Leeuwenhoek could pull the hot section apart like
taffy to create two long whiskers of glass. By then reinserting the
end of one whisker into the flame, he could create a very small, high-quality
glass sphere. These spheres became the lenses of his microscopes, with
the smallest spheres providing the highest magnifications. An experienced
businessman, Leeuwenhoek realized that if his simple method for creating
the critically important lens was revealed, the scientific community
of his time would likely disregard or even forget his role in microscopy.
He therefore allowed others to believe that he was laboriously spending
most of his nights and free time grinding increasingly tiny lenses to
use in microscopes, even though this belief conflicted both with his
construction of hundreds of microscopes and his habit of building a
new microscope whenever he chanced upon an interesting specimen that
he wanted to preserve.
good use of the huge lead provided by his method. He studied a broad
range of microscopic phenomena, and shared the resulting observations
freely with groups such as the English Royal Society. Such work firmly
established his place in history as one of the first and most important
explorers of the microscopic world. With regards to the construction
of his microscopes, however, Leeuwenhoek maintained throughout his life
that there were aspects of their construction "which I only keep
for myself," including in particular his most critical secret of
how he created lenses.
by the English Royal Society and later discoveries
After developing his method for creating powerful lenses and applying
them to a thorough study of the microscopic world, Leeuwenhoek was introduced
via correspondence to the English Royal Society by the famous Dutch
Physician Regnier de Graaf. He soon began to send copies of his recorded
microscopic observations to the Royal Society. In 1673 his earliest
observations were published by the Royal Society in its journal: Philosophical
Transactions. Amongst these published observations were Van Leeuwenhoek's
accounts of bee mouthparts and stings... .
Despite the initial
success of Van Leeuwenhoek's relationship with the Royal Society, this
relationship was soon severely strained. In 1676 his credibility was
questioned when he sent the Royal Society a copy of his first observations
of microscopic single celled organisms. Heretofore, the existence of
single celled organisms was entirely unknown. Thus, even with his established
reputation with the Royal Society as a reliable observer, his observations
of microscopic life were initially met with certain skepticism. Eventually,
in the face of Van Leeuwenhoek's insistence, the Royal Society arranged
to send an English vicar, as well as a team of respected jurists and
doctors to Delft, Holland to determine whether it was in fact Van Leeuwenhoek's
ability to observe and reason clearly, or perhaps the Royal Society's
theories of life itself that might require reform. Finally in 1680,
Van Leeuwenhoek's observations were fully vindicated by the Society.
vindication resulted in his appointment as a Fellow of the Royal Society
in that year. After his appointment to the Society, he wrote approximately
560 letters to the Society and other scientific institutions over a
period of 50 years. These letters dealt with the subjects he had investigated.
In 1981 The British
microscopist Brian J. Ford found that Leeuwnehoek's original specimens
had survived in the collections of the Royal Society of London. They
were found to be of high quality, and were all well preserved. Ford
carried out observations with a range of microscopes, adding to our
knowledge of Leeuwenhoek's work.
Amongst Van Leeuwenhoek's
many discoveries are: in 1674 he discovered infusoria (dated zoölogical
category,) in 1676 he discovered bacteria, in 1677 he discovered spermatozoa
and in 1682 he discovered the banded pattern of muscular fibers.
He died at the age
of 90, on August 30, 1723 at Delft.
of van Leeuwenhoek's discoveries
Van Leeuwenhoek was a Dutch Reformed Calvinist. He often referred with
reverence to the wonders God designed in making creatures great and
small. He believed that his amazing discoveries were merely further
proof of the great wonder of God's creation.
discoveries did overturn the traditional belief of the time in the spontaneous
generation of life. This belief or theory was generally
held by the 17th century scientific community, and was also tacitly
endorsed by the 17th century Church. Still, the Church's position on
the exact nature of spontaneous generation was ambivalent. Possibly
because van Leeuwenhoek's discoveries of microscopic life appeared at
the time to pose no direct challenge to any Church doctrines such as
the doctrine of creationism, the Church made no effort to challenge
or question any of van Leeuwenhoek's discoveries in any way.
van Leeuwenhoek, of Delft, belongs the high merit of having been the
first to use the microscope systematically and of having brought the
construction of the simple microscope in his own hands to a high degree
of perfection . . . Self-taught and never having attended a university,
ignorant of Latin and Greek and of the classical texts, he became one
of the greatest and most expert microscopists, thanks to the sagacity
of his observations and the perfection of his technique"
(Arturo Castiglioni, A history of medicine).
With skill, diligence,
an endless curiosity, and an open mind free of the scientific dogmas
of the day, Leeuwenhoek succeeded in making some of the most important
discoveries in the history of biology. He was the first to observe bacteria
and protozoa. His research on lower animals refuted the doctrine of
spontaneous generation, and his observations helped lay the foundations
for the sciences of bacteriology and protozoology.
Antonie van Leeuwenhoek
was the son of Philips Thoniszoon, a basket-maker, and Margriet Jacobsdochter
van den Berch, who came from a family of brewers. He took his surname
- «Lion’s Corner» - from the corner house near the
Leeuwenpoort - «Lion’s Gate» - at Delft, which was
owned by his father. The family belonged to the prosperous middle class
of artisans, brewers, and lesser public officials, which was typical
of the Golden Age of the Dutch Republic.
Little is known
of Leeuwenhoek's early life, but it is certain that he did not have
an extensive scientific education. When his father died at an early
age, in 1638, the fourteen year old Antonie Leeuwenhoek was sent to
the grammar school of Warmond, a village near Leiden. For some time
afterwards he lived in Benthuizen with an uncle who provided him with
a foundation in mathematics and basic physics. When his uncle died in
1648, Leeuwenhoek, now sixteen years old, left for Amsterdam to learn
a trade, opting for an apprenticeship in the Cloth Worker’s Guild.
He became apprenticed in a linen-draper’s shop.
Returning to Delft
when he was 20, he established himself as a draper and haberdasher.
At the age of 22 he was a successful textile merchant, purchased a house
and an adjoining shop in Delft, where he was to spend the rest of his
On July 29, 1654,
he married Barbara de Mey, daughter of Elias de May, a serge merchant
from Norwich, England. Of their five children only one, their daughter
Maria, survived her father.
His reputation rose
so that in 1660 he was able to take up a new career as a civil servant
with an appointment to usher to the aldermen of the municipality of
In 1666 Leeuwenhoek
was named Chamberlain of the Council Chamber of the Worshipful Sherriffs
of Delft. That was the year his wife died, and two years later Leeuwenhoek
made one of the only two foreign trips that he took in his lifetime,
visiting the chalk hills of Gravesend and Rochester in Kent. His other
occasion for travel abroad was a journey that he made to Antwerp in
1698 to see the Jesuit scholar Daniel Papenbroek. Upon his return to
delft in 1699 he was appointed surveyor to the court of Holland.
In the meantime
Leeuwenhoek continued to advance in the service of the city of Delft,
being made chief warden of the city in 1677 and, because of his mathematical
skills, “wine and liquor gauger” (or inspector of weights
and measures) in 1679. The income and emoluments from these offices
made him financially secure, especially in his old age, when the municipality,
in gratitude for his scientific achievements, granted him a pension.
on January 25, 1671. His second wife was Cornelia Swalmius, the daughter
of Johannes Swalmius, a Calvinist minister at Valkenburg, near Leiden.
She died in 1694; the one child of this marriage did not survive infancy.
It probably that his second wife, who was an educated women, gave Leeuwenhoek
the impetus to his scientific activity. The income from his public offices
as well as a family inheritance gave him sufficient resources to launch
his exploration of the microscopic worlds.
In 1676 he served
as the trustee of the estate of the deceased and bankrupt Jan Vermeer,
the famous painter, who had been born in the same year as Leeuwenhoek
and is thought to have been a friend of his.
At the time of his
appointment in 1666 he had already begun to broaden his scientific horizons,
studying navigation, astronomy, mathematics and natural sciences.
Leeuwenhoek’s scientific life may be said to have begun in about
1671, when he was thirty-nine years old. At that time, developing the
idea of the glasses used by drapers to inspect the quality of cloth,
he constructed his first simple microscope or magnifying glasses, consisting
of a minute lens, ground by hand from a globule of glass, clamped between
two small perforated metal plates.
He seems to have
been inspired to take up microscopy by having seen a copy of Robert
Hooke’s illustrated book Micrographia, which depicted Hooke’s
own observations with the microscope and was very popular.
It was through his
letters - more than 300 of them, written to private scientists and amateurs
in both Holland and other countries - that Leeuwenhoek made his work
known. He wrote exclusively in Dutch, but had a few of his letters translated
for the benefit of his correspondents. It was his friend Regnier de
Graaf (1641-1693) who made sure that Leeuwenhoek's achievements became
known to a wider audience. De Graaf put Leeuwenhoek in contact with
the Royal Society in London, to which he communicated most of his discoveries
in papers in the form of a lengthy correspondence with Henry Oldenburg,
the Society’s secretary. His first letter, of 1673, contained
some observations on the stings of bees. His letters, written in Dutch,
were translated into English or Latin and printed in the Philosophical
Transactions of the Royal Society, and often reprinted separately. All
together he sent 190 papers to the Royal Society, to which he also donated
Leeuwenhoek made his most important discovery early in his scientific
career, in 1674, when he recognized the true nature of microorganisms.
He began to observe bacteria and protozoa, his "very little animalcules,"
which he was able to isolate from different sources, such as rainwater,
pond and well water, and the human mouth and intestine. Starting from
the assumption that life and motility are identical, he concluded that
the moving object that he saw through his microscope were little animals.
He recorded these
observations in his diary, and two years later, in a letter of October
9, 1676, communicated them to the Royal Society, where they caused a
sensation. Indeed, such was the disbelief of some of fellows of that
body that Leeuwenhoek felt obliged to procure written attestations to
the reliability of his observations from ministers, jurists, and medical
men. Leeuwenhoek subsequently described, in about thirty letters to
the Royal Society, many specific forms of microorganisms, including
bacteria, protozoa, and rotifers, as well as his incidental discovery
of ciliate reproduction.
The boys in the
In letters to the Royal Society of London of 1699, later 1701, he mentions
male and female sperm animals: Hoc videns mihi imiginabar, alterum esse
masculinum, alterum femininum. I have often observed the sperm of a
healthy man without waiting for it to become corrupt or fluid/watery,
five or six minutes after ejaculation. I have noticed that a large number
of small animals, I think it must be more than a thousand, on an area
no larger than a grain of sand."
the terms animalculi e semini, animalculi seminis, vermiculi minutissimi
in the same way. The totality of it he called semen masculorum.
It was necessary
to devise a scale by which to measure this formerly invisible new world,
and Leeuwenhoek therefore developed a practical system of micrometry,
utilizing as standards a grain of coarse sand (870 µ), a hair
from his beard (100 µ), a human erythrocyte (7,2 µ), and
bacteria in peppe-water (2-3 µ).
In 1677 Leeuwenhoek
described for the first time the spermatozoa from insects, dogs, and
man. He was drawn to the investigation of animal reproduction when Stephen
Ham of Arnhem, a medical student, told him that he had seen animalcules
in human seminal fluid. Ham presumed that these little animals had been
generated by putrefaction; Leeuwenhoek, however, supposed them to be
a normal component of semen throughout the animal kingdom. He described
the semen as "sperm animals", sperm cells, which he considered
to be the nucleus of the new individual, while the egg cell was supposed
to be just nourishment for the sperm animal". In the course of
forty years, he described the spermatozoa of arthropods, molluscs, fishes,
amphibians, birds, and mammals.
on the life histories of various low forms of animals were in opposition
to the doctrine that they could be produced spontaneously or bred from
corruption. Thus, in 1680 he noticed that yeast consist of minute globular
particles. Thus, he showed that the weevils of granaries (in his time
commonly supposed to be bred from wheat as well as in it) are really
grubs hatched from eggs deposited by winged insects.
He discovered the
"animalcules" in the tartar on his teeth and, even after meticulous
cleansing, the remaining opaque deposits isolated between his teeth
"as thick as if it were batter". These deposits, he observed,
contained a mat of various forms of bacteria.
Since he believed in all living forms to be functionally similar to
one another, Leeuwenhoek also made extensive investigations of reproduction
in plants. In a letter of October 12, 1685, he drew upon his studies
of the seeds of angiosperms to explain his theory of plant reproduction:
since motionless plants could not copulate, each individual had to provide
for its own propagation. The embryonic plant was therefore the source
of new life; the endosperm was the primary nutritive uterus and the
earth the secondary nutritive uterus for the seed of the plant. Since
he considered the flower to be beautiful but functionless ornament of
the plant, Leeuwenhoek did not investigate the anthers and the ovaries.
Leeuwenhoek was particularly attentive to the blood vessels and the
blood. Harvey had described the circulation of the blood in 1628, while
Malpighi discovered the capillaries in 1661 and, in 1665, observed the
corpuscles for the first time (although he wrongly identified them as
fat globules). Malpighi in 1684 gave the first accurate description
of red blood cells. Leeuwenhoek, unaware of Malpighi’s work, effectively
rediscovered the blood corpuscles, in 1674, and the blood capillaries
Beginning in 1679,
the French Journal Recueil d’expériences et observations
sur le combat qui procède du mélange des corps published
Leeuwenhoek's letters, translating them from the Philosophical Transactions.
Leeuwenhoek himself did not publish his work until 1684, when he brought
out some of his letters in Dutch. From 1687 he adopted a more systematic
course of publication, however, and in 1718 he brought out a collected
edition of his letters in Dutch, followed in 1722 by a Latin edition.
In his observation
on rotifers in 1702, Leeuwenhoek remarked that, "In all falling
rain, carried from gutters into water-butts, animalcules are to be found;
and that in all kinds of water, standing in the open air, animalcules
can turn up. For these animalcules can be carried over by the wind,
along with the dust floating in the air."
Of major importance
were his description of the optic lens in many species of animals. Leeuwenhoek
studied the structure of the optic lens, and he demonstrated the striation
in skeletal musculature. In 1719 he introduced histological staining,
using saphron for investigating muscle fibres.
His letter on the flea, in which he not only described its structure
but traced out the whole history of its metamorphosis, beginning with
its first emergence from the egg, is of great interest, not so much
for the exactness of his observations as for illustration of his opposition
to the spontaneous generation of many lower organisms, such as "this
minute and despised creature." Some asserted that the flea was
produced from sand, others form dust, etc. but Leeuwenhoek showed it
to be "endowed with as great perfection in its kind as any large
animal" and proved that it bred in the regular way of winged insects.
Ants and mussels
Leeuwenhoek also carefully studied the history of the ant and was the
first to show that what had been reputed to be ants' eggs, were really
their pupae, containing the perfect insect nearly ready for emergence,
and that the true eggs were much smaller and gave origin to maggots,
or larvae. He argued that the sea mussel and other shellfish were not
out of sand found at the seashore or mud in the beds of rivers at low
water but from spawn, by the regular course of generation. He maintained
the same to be true of the freshwater mussel, whose embryos he examined
so carefully that he was able to observe how they were consumed by "animalcules,"
many of which, according to his description, must have included ciliates
in conjunction, flagellates, and the Vorticella. Similarly he investigated
the generation of eels, which were at that time supposed to be produced
from dew without the ordinary process of generation.
A man unto himself
Despite his achievements and the respect he enjoyed in the Royal Society
of London, Leeuwenhoek remained in relative scientific isolation. One
consequence of this was that he was not always fully acquainted with
the researches and theories of his fellow scientists, and so could not
incorporate their sometimes valuable suggestions into his own work.
But he was thus able to work with full independence and to make sharp
distinction between the empiricism and speculation that marked the sometimes
chaotic world of seventeenth-century science.
To his work in lens-grinding
Leeuwenhoek brought a good pair of eyes, mathematical exactitude, great
patience, and even greater manual dexterity. These same qualities, together
with a keen, practical intellect, served him in the exploration of the
whole field of natural science that occupied him in fifty years of continuous
work. Strictly speaking, his scientific training was incomplete - he
never attended a university - and he was limited by his lack of skill
in classical and foreign languages. He was, however, able to rely upon
such friends as Regnier de Graaf and Constantijn Huygens (1596-1687)
as well as upon professional translators to aid him. He derived much
of his scientific knowledge from Dutch authors - for example, Cornelis
Bontekoe (1640-1685) on medicine and Jan Swammerdam (1637-1680) on insects
- and from Dutch translations of standard works, or, indeed, from illustrations
of books that he was not otherwise able to read - Robert Hooke (1635-1703)
on microscopy, Nehemiah Grew (1641-1712) on plant anatomy, and Francesco
Redi (1626-1697) on insects). He gained new information, too, from his
correspondence with the Royal Society and from conversations with visiting
work and microscopes
About 1671, when he was thirty-nine years old, Leeuwenhoek began developing
the idea of the glasses used by drapers to inspect the quality of cloth.
He constructed his first simple microscope or magnifying glasses, consisting
of a minute lens, ground by hand from a globule of glass, clamped between
two small perforated metal plates. To this apparatus he fixed a specimen
holder that revolved in three planes. From these beginnings Leeuwenhoek
went on to grind more than 400, maybe as many as about 550 lenses in
In basic design,
probably all of Leeuwenhoek’s instruments were simply powerful
magnifying glasses, not compound microscopes of the type used today.
Compared to modern microscopes, it is an extremely simple device, using
only one lens, mounted in a tiny hole in the brass plate that makes
up the body of the instrument. The specimen was mounted on a sharp point
that sticks up in front of the lens, and its position and focus could
be adjusted by turning two screws. The entire instrument was only 8-10
cm long, and had to be held close to the eye; it required good lighting
and great patience to use.
(that is, microscopes using more than one lens) had been invented around
1595, nearly forty years before Leeuwenhoek was born. Several of Leeuwenhoek's
predecessors and contemporaries, notably Robert Hooke in England and
Jan Swammerdam in the Netherlands, had built compound microscopes and
were making important discoveries with them. These were much more similar
to the microscopes in use today. Thus, although Leeuwenhoek is sometimes
called "the inventor of the microscope," he was no such thing.
of various technical difficulties in building them, early compound microscopes
increased the problem of chromatic aberration and were not practical
for magnifying objects more than about twenty or thirty times natural
size. A master lens grinder, Leeuwenhoek made microscopes consisting
of a single, high-quality lens of very short focal length. Together
with his naturally acute eyesight and great care in adjusting the lighting
where he worked, enabled him to build microscopes that magnified over
200 times, with clearer and brighter iimages than any of his colleagues
could achieve. What further distinguished him was his curiosity to observe
almost anything that could be placed under his lenses, and his care
in describing what he saw. Although he himself could not draw well,
he hired an illustrator to prepare drawings of the things he saw, to
accompany his written descriptions. Most of his descriptions of microorganisms
are instantly recognizable.
his microscopy techniques a secret, and they are still much of a mystery.
In his life he grinded more than 400 lenses, of which most were very
small, some of them not larger than a needle’s head. They were
mounted between two thin brass plates riveted together. A large collection
of his lenses was bequeathed to the Royal Society of London, and they
have been found to have magnifying degrees of 50 upwards. The best that
survives of his lenses, in the University Museum of Utrecht, has a linear
magnifying power of 270 times and a resolving power of 1,4 µ.
From his recorded
observations it may be surmised that he must have actually made lenses
of 500 power, with a resolution of 1,0 µ. In order to observe
phenomena as small as bacteria, Leeuwenhoek must have employed some
form of oblique illumination, or other technique, for enhancing the
effectiveness of the lens, but this method he would not reveal. We know,
however, that he used a reflector of polished copper. Whatever his methods,
Leeuwenhoek’s instrument were not surpassed until the nineteenth
been condemned for failing to link microorganisms to transmissible diseases.
It is argued that, in his appreciation of the wonder of microbes in
the firmament of living organisms, Leeuwenhoek was closer to a true
appreciation of their role in the conduct of a global ecology than much
contemporary science. He described Giardia lamblia i his own faeces.
Leeuwenhoek’s scientific achievements were recognised during his
lifetime by both his colleagues and the public. In 1680 he was elected
a fellow of the Royal Society of London; in 1699 he was appointed a
correspondent of the Paris Académie des sciences; and in 1716
the Louvain College of Professors awarded him a silver medal. In addition
to the pension that it gave him, the municipality of Delft made him
special awards upon the publication of several of his books.
The dramatic nature
of his discoveries made him world famous, and he was visited by many
notables in his former dry-goods shop. The increasing number of learned
and eminent visitors from several countries eventually caused Leeuwenhoek
to demand introductory letters; his guests included kings and princes,
among them James II of England, Frederick the Great of Prussia, Elector
August II of Saxony, and the Grand Duke Cosimo of Tuscany. Peter the
Great of Russia in 1798 visited him during his great European journey.
On that occasion Leeuwenhoek demonstrated circulation in the capillaries
of an eel to the tsar.
In his old age,
Leeuwenhoek became a legend; to his displeasure, his fellow townsmen
reverently referred to his as a magician.