1668: Leeuwenhoick completes Harvey's work

Anton van Leeuwenhoik (1632-1723)

William Harvey proved blood circulated through the body in 1628, although he could not see where veins and arteries connected. Marcello Malpighi observed where arteries and veins connected, although he considered it to be of little significance.  It wasn't until 1668, when Antony Leeuwenhoek observed these same connections, that the work of Harvey had been completed.

Anton (Antony) van Leeuwenhoek was born in Delft, Holland, on October 24, 1632.  His father was a basket maker, and his mother was from a family of "well-to-do" brewers, and so he had "an easy going life, said Garrison, "the greater part of which was devoted to the study of natural history."  (11, page 251)rcu

He was well educated a a child, and, in 1648, he left Delft to live with his uncle at  Benthuizen, where he was apprenticed in a linen-draper's shop (made linen products). In 1654 he returned to Delft and set up his own shop as a draper, although he also worked as a surveyor, a wine assayer, and as a minor city official. (18)

Leeuwenhoek's microscope

was a very powerful magnifying glass

It was a very simple device

that used only one lens,  

that is mounted in a tiny hole

in the brass plate that makes up 

the body of the instrument. 

The specimen was mounted 

on the sharp point that sticks up 

in front of the lens.  

Its position and focus could be adjusted

by turning the two screws.

The instrument was 3-4 inches long,

and had to be held up close to the eye.

It required good lighting and great patience.

This was a significant accomplishment

considering the compound microscope

was invented in 1595,

and had already been used 

by Robert Hooke

and Jan Swammerdam.

(18)

He was not well off financially as an adult, and there were no signs he would become one of the most significant scientists of his era.  However, perhaps inspired by Robert Hooke's book Micrographia,  by 1668 he had learned to grind lenses, and he made simple microscopes, using them to investigate plants and animals.  Over time he would end up with a collection of over 247 microscopes with 419 lenses, most of which he made himself.  (11, page 251)(18)

A neat thing about his microscope was that it was a simple microscope that used one lens. This was significant because a compound microscope similar to the one used today had been invented in 1595 and had been used by Robert Hooke and Jan Swammerdam to make significant discoveries.  (18)

However, compound microscopes were complicated to make, and it was not possible to magnify objects greater than twenty or thirty times their natural size. Due to Leeuwenhoek's skill at grinding lenses and adjusting lighting, he became skilled at observing microscopic structures up to 200 times their natural size. (18)

Perhaps for this reason alone, became such a significant investigator of the microscopic unknown, so significant that the director of the East India Company, said Garrison, sent him specimens, and even Peter the Great visited his collection in 1689.  He even donated 26 of his microscopes to the London Royal Society, of which he later became a member. (11, page 251)

Garrison said:

Leeuwenhoek was a strong man of marvelous industry, and during his long life he sent as many as 375 scientific papers to the Royal Society and 27 to the French Academy of Sciences.  (11, page 251)

He ended up "with skill, diligence, an endless curiosity, and an open mind free of t scientific dogma of his day."  This allowed him to become one of the most significant physicians and scientists of his era, making many of the "most important discoveries in the history of biology." (18)

He was the first person to visualize, or at least the first to report seeing: (11, page 251)

• Sperm cells (1674)
• Striped character of voluntary muscle (1675
• Protazoa (1675)
• Microorganisms (bacteria) in the teeth (1683)  (11, page 251)

By finding microorganisms in the teeth, he became the first person to accurately describe the "chains and clumps"associated with bacteria.  (11, page 251)

His most significant observation, at least for our history, was his observation of red blood cells in 1664 and capillary anastomosis connecting arteries and veins in 1668.  (11, page 252)

He was not the first to observe either, as Swammerdam was the first to describe red blood corpuscles and Malpighi also described them.  Malpighi was the first to describe capillary anastomosis connecting where arteries and veins came together, although he did not consider it a significant find.

Leeuwenhoek was the first to give a complete account of red blood cells, and he was the also first to consider capillary anastomosis as being a significant find. 

Garrison said:

It was Malpighi's discovery and Leeuwenhoek's thorough work on the capillary circulation which finally completed Harvey's demonstration. (11, page 252)

So while Galen might have suspected blood circulates as far back as the 2nd century, it wasn't described until the 16th century by Servetus, and proved until the 16th century by Harvey.  Yet with the observations of Malpighi and Leeuwenhoek, for the first time the circulation of blood could be traced through the entire body. 

References:

1. Tissier
2. Lagerkvist, Ulf, "The Enigma of Ferment," 2005, Singapore, World Scientific Publishing
3. Potter, Elizabeth, "Gender and Boyle's Law of Gases," 2001, Indiana University Press
4. Newman, William R, et al, "Alchemy Tried in the Fire," 2002, University of Chicago
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8. Hamilton, William, "A History of Medicine, Surgery and Anatomy," 1831, Vol. I, London, New Burlington
9. Osler, William Henry, "The evolution of Modern Medicine: A series of lectures delivered at Yale University on the Sillman Foundation in April, 1913," 1921, New Haven, Yale University Press
10. Osler, ibid, pages 170, reference referring to William Harvey: Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus, Francofurti, 1628, G. Moreton's facsimile reprint and translation, Canterbury, 1894, p. 48. 20 Ibid., p. 49.
11. Garrison, Fielding Hudson, "Introduction to the history of medicine," 1921, London, 
12. Baker, Christopher, editor, "The Great Cultural Eras of the Western World: Absolutism and the Scientific Revolution 1600-1720: A biographical dictionary," 2002, CT, Greenwood Publishing; Herman Boerhavve published Biblia Naturae (Bible of Nature) in 1737, which was a two volume compilation of the works of Jan Swammerdam. Can you read Latin?
13. Garrison, op cit, 266; (Samuel) Pepy's Diary, Mynors Bright's ed., London, 1900, v, 191
14. Bradford, Thomas Lindsley, writer, Robert Ray Roth, editor, “Quiz questions on the history of medicine from the lectures of Thomas Lindley Bradford M.D.,” 1898, Philadelphia, Hohn Joseph McVey
15. Brock, Arthur John, "Galen on the natural faculties," 1916, London, New York, William Heinemann, G.P. Putnam's Sons
16. "History of Chemistry," historyworld.net, http://www.historyworld.net/wrldhis/PlainTextHistories.asp?ParagraphID=kpt, accessed 7/6/14
17. Affray, Charles, Denis Noble, "Origins of Systems Biology in William Harvey's masterpiece on the Movement of the Heart and the Blood in Animals," April 17, 2009, International Journal of Molecular Sciences, 10(2), pages 1658-1669, found online at ncbi.nlm.hih.gov, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2680639/, accessed 7/8/14
18. "Antony van Leeuwenhoik (1632-1723)," ucmp.berkeley.edu, http://www.ucmp.berkeley.edu/history/leeuwenhoek.html

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