Wrote Letter L-128 of 1683-07-16 to Christopher Wren about the procreation of frogs, sperm in fowl's egg, reproduction of rabbits, little animals in frog intestines, a theory about digestion in humans and fish, and blood

Date:

July 16, 1683

Standard reference information

L-number:

L-128

Leeuwenhoek's number:

Collected Letters number:

Collected Letters volume:

Text of the letter in the original Dutch and in English translation from Alle de Brieven / The Collected Letters at the DBNL - De Digitale Bibliotheek voor de Nederlandse Letteren.

The original manuscript on 22 quarto pages, written and signed by Leeuwenhoek, is preserved at the Royal Society (MS. 1897. Early Letters L1.68).

Leeuwenhoek's summary

From the three editions of Onsigtbare verborgentheden and translated into Latin for all of the editions, some re-titled, of Anatomia Seu Interiora Rerum.

Ontledingen en Ontdekkingen. Van de voort-teelinge des Kik-vors, desselfs Mannelijk Saad, Bloed, Vleesch, Bloed-vaten, ende Dierkens in de excrementen van de selve. Van de voort-teelinge van Vogelen ende Visschen. Gestalte van de vleesch-musculen. Verbrijselinge van de spijs in de maag en darmen. Excrementen van Cabbbeljauw. Groote beweging van het hart, en minder ommeloop van het bloed, en dat het hert door een al te lange uytrekkinge niet en kan weder inkrimpen.

Dissections and discoveries. Of the procreation of frogs, the male seed, blood, flesh, and blood vessels of the same, and little animals in the excrement of the same. Of the procreation of birds and fish. The structure of the flesh muscles. The crushing of food in the stomach and guts. The excrement of cod. Great movement of the heart, and less circulation of the blood, and that the heart through an already too long drawing out cannot shrink again.

Reception in London

Less than three weeks after Leeuwenhoek wrote this letter, it was received in London (Birch's History, vol. IV p. 217), where it caused some discussion:

It was observed upon Mr. Leeuwenhoeck's letter of July 16th, that the point, where the animal of the male seed is to be first received, and where it is to be first nourished, is placed in the yolk of the egg; and accordingly, that Mr. Leeuwenhoeck made search for the animal in the yolk of the egg: whereas he ought to have looked for it in the white; which is certainly the first nourishment of the chicken, the colliquamentum being there to be found after twelve hours incubation.

It remained to know, whether Mr. Leeuwenhoeck by the abovementioned point did not mean the cicatricula, which adheres to the yolk of the egg.

Mr. Leeuwenhoeck having hitherto been unsuccessful in tracing the animal, it was desired, that he would examine a greater variety of eggs, and particularly those of a silk-worm.

What about Leeuwenhoek's relationship with the Royal Society?

In the previous Letter 37 of January 22, 1683, he noted that he had not received any copies of Philosophical Transactions for years. Apparently, he did not have a complete set prior to that, either. In this next letter, he wrote:

In my letter of August 14th 1675 I wrote to Mr. Oldenburg that in my opinion the food is crushed in the stomach. But that Gentleman has not published this in print as far as I know.

He was referring to Letter 12. In fact, that letter was published in Philosophical Transactions Vol. X, No. 117 on September 26, 1675. An extract was on pp. 380-385 preceded by an extract from Letter 15 of April 21, 1676 on pp. 378-380. Not knowing that, Leeuwenhoek was even further motivated to publish his letters himself, which he began to do the six months later.

In the last paragraph of this Letter 38, he wrote:

A few days ago I at last received from London the missing Transactions.

Specimens and methods

"I kicked the frog with my foot."

Leeuwenhoek spent most of this letter responding to other researchers. However, in the first part of this letter, he recounted in great detail how he dissected a series of frogs, paying special attention to its bodily fluids. He did not have to go far to get his specimens.

The first frog that I dissected sat in the road, and seemed so weak from the cold that, though I kicked it with my foot, it did not jump away. Picking it up and opening it, I found it was a female.

Response to other researchers

In addition to the ongoing discussions with local physicians, Leeuwenhoek responded to their published writing.

A certain Doctor, writing about generation says among other things, in the margin, as follows: Should a fetus grow from the male semen, an arm or a leg would easily get lost. This he enlarges in the text. But methinks, under correction, that it would suffice to give what follows as a proof enabling me to maintain that the fetus proceeds only from the male semen and that the female only serves to feed and develop it.

Alle de Brieven / Collected Letters notes that the quotation comes from Dionisius van der Sterre's recently published book, Voorstelling van de noodsaakelijkheid der keijserlijke snee (cover on right; click to enlarge). It was printed by Leiden bookseller Daniel van Gaesbeeck, who two years later would publish six of Leeuwenhoek's early letters, though not this Letter 38. Voorstelling was dedicated to Leeuwenhoek's friend Cornelis 's Gravesande.

Continuing the discussion above about local physicians, Leeuwenhoek wrote more about the one who had intended to write about him. Alle de Brieven / Collected Letters identifies this physician as Cornelis Bontekoe and the book as 1682's Reden over de koortzen:

In a little book which recently appeared from his hand, he writes that there is no fermentation in the blood, and, when speaking about the circulation of the blood, he says that, though the heart and the pulse beat rapidly, the circulation of the blood is none the quicker. This had been my opinion long before I spoke about it to this physician, and when I was asked what might be the reason I replied as follows.

The public and their opinions

"I shall be contradicted by many all over the world."

He began this letter by noting the controversy over some of his ideas.

Mr Francis Aston, Secretary of the Royal Society, on the 16th/26th Febr. 1682/832) wrote to tell me i.a. that my theory of animal generation through male seed is very ingenious but that I shall be contradicted by many all over the world. That is exactly what I thought, for the world is prejudiced in favor of the ovary. However, I have found many learned gentlemen in our country who approve my theses. Consequently I shall continue my observations and contemplations on this subject.

How did Leeuwenhoek see himself understood by his countrymen? He spent a lot of time with physicians, the professionals who were most interested in his observations.

Many clever people in our country take great pleasure in my theses.

This pleasure involved some disagreement.

In my last letter I said that there is no fermentation in the blood. For some years I have tried to maintain this against several physicians, and among other things also in what manner the blood is propelled in our body. ...

Among the physicians there was one who often visited me and who told me in the presence of other gentlemen that he took great pleasure in my assumptions; that after leaving me some time ago with another doctor who had been one of our party they had philosophized the whole evening about my arguments; that he was going to write about it but that I should have all the credit, since he did not wish to plume himself on borrowed thoughts. However, I have not found it in the booklets he has published since that day, so that I presume the said gentleman has forgotten all about it.

Figures

The original drawings are lost. The Dutch and Latin editions that Leeuwenhoek published used the same plates, one for each figure, placed near the text discussing it. The scans on the left sidebar came from the 1708 third edition of Arcana Naturae Microscopiorum.

In the text, Leeuwenhoek noted that he drew Figs. 1 and 3. The other three were well within his technical capabilities. Referring to Fig. 1, he wrote:

However, I have figured them as best I could.

He noted that he made Fig. 3 to show something new.

Because the circular constrictions or wrinkles of each separate fiber were more numerous than I had hitherto seen in the fibres of the flesh of an ox, a fly, a gnat, a flea and a louse, I made a drawing of a small bit of one of the fibres composing a frog's muscle, as in fig. 3.

In the manuscript, he did not give the third figure a number. He treated it as a plate and called them Fig. A, Fig. B, and Fig. C. However, in print, they became Fig. 3 A, Fig. B, and Fig. C.

In the manuscript, the fourth and fifth figures were numbered Fig. 3 and Fig. 4. However, in print, they became Fig. 4 and Fig. 5.

Publication history

Related sources, especially Philosophical Transactions, and first editions only of Leeuwenhoek's volumes of letters. For later editions see Related events under Learn more.

Year	Author	Title
1665	various	Philosophical Transactions
1682	Bontekoe, C.	Reden over de koortzen
1683	Leeuwenhoek, A. van	An Abstract of a Letter from Mr. Anthony Leeuwenhoeck of Delft about Generation by an Animalcule of the Male Seed. Animals in the Seed of a Frog. Some Other Observables in the Parts of a Frog. Digestion, and the Motion of the Blood in a Feavor
1684 - 1718	various	Nouvelles de la republique des lettres
1685	Leeuwenhoek, A. van	Anatomia et Contemplatio
1685	Leeuwenhoek, A. van	Onsigtbare verborgentheden
1687	Leeuwenhoek, A. van	Anatomia Seu Interiora Rerum
1754 - 1787	Berryat, J. (ed.)	Collection académique
1779 - 1780	Leske, N. G.	Abhandlungen zur Naturgeschichte, Physik und Oekonomie
1952	Leeuwenhoek, A. van	Alle de Brieven. The Collected Letters. Volume 4

Other publications:

Three months after it was written, an extract of this letter was published in Philosophical Transactions vol. 13 no. 152 for October 20, 1683, and included all of the figures.

The following year, 1684, an extract was published in Nouvelles de la republique des lettres, including Figure 1 with the little animals.

Fifty years after Leeuwenhoek's death, an excerpt from the Philosophical Transactions extract was published in Collection académique vol. VII pp. 57-58. It had none of the figures.

In 1780, an excerpt including three of the five figures was published in Abhandlungen zur Naturgeschichte, Physik und Oekonomie.

Learn more

Related letters:

What Leeuwenhoek wrote ...
Wrote Letter L-126 of 1683-05-20 to Anthonie Heinsius about generation and about the circulation of the blood, which he intends to communicate in a letter to the Royal Society
Wrote Letter L-173 of 1686-04-02 to members of the Royal Society about the structure of bone, the bark of trees, skin and scales, the moisture evaporating from his body, and a little peeling piece of skin

The adventures of Letters 38, 42, and 43

Period 2 - 1679-1686

Structure of the letters in Period 2

1683-84: Contradicted by many

Specimens: Sperm

Related people:

Christopher Wren

Related events:

Date	Event
January 1, 1682	Visited by Cornelis Bontekoe
July 28, 1683	The Royal Society read Letter L-128 of 1683-07-16 about reproduction, little animals, digestion, and blood
August 4, 1683	The Royal Society discussed Letter L-128 of 1683-07-16 about the male seed in egg yolks
September 10, 1683	Anthonie Heinsius wrote Letter L-133 to Leeuwenhoek about recent observations of generation
January 1, 1685	Published Onsigtbare Verborgentheden (Invisible Mysteries), Letters 38, 42, 43 (L-152, L-150, L-128)
January 1, 1685	Published Anatomia et Contemplatio (Anatomy and Contemplation), Letters 43, 42, 38 (L-128, L-150, L-152)
February 5, 1685	Visited by Thomas Molyneux on behalf of the Royal Society
January 1, 1687	Published Anatomia Seu Interiora Rerum (Interior Anatomy), 19 Letters from 28 - 52
January 1, 1687	Published Anatomia Seu Interiora Rerum (Interior Anatomy), Letters 43, 42, 38
January 1, 1691	Published Onsigtbare Verborgentheden (Invisible Mysteries), Letters 38, 42, 43 (2nd)
January 1, 1696	Published Arcana Naturae Microscopiorum (Nature's Mcroscopical Mysteries), 19 Letters from 28 - 52 (2nd)
January 1, 1698	Published Onsigtbare Verborgentheden (Invisible Mysteries), Letters 38, 42, 43 (3rd)
January 1, 1708	Published Arcana Naturae Microscopiorum (Nature's Mcroscopical Mysteries), 19 Letters from 28 - 52 (3rd)
January 1, 1722	Published Opera Omnia, seu Arcana Naturae Microscopiorum (The Works, or Nature's Microscopical Mysteries), 25 Letters from 28 - 60 (4th)

Top Menu - main site navigation

Which number?

Life in Holland

in the 1600's

Work in Holland

in the 1600's

Wrote Letter L-128 of 1683-07-16 to Christopher Wren about the procreation of frogs, sperm in fowl's egg, reproduction of rabbits, little animals in frog intestines, a theory about digestion in humans and fish, and blood

"I kicked the frog with my foot."

"I shall be contradicted by many all over the world."

Figures

Life in Holland

in the 1600's