Wrote Letter 53 of 1687-04-04 (AB 98) to Members of the Royal Society

April 4, 1687
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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, written by a copyist and signed by Leeuwenhoek, is preserved at the Royal Society (MS. 1917. L 2. 8).

Reception in London

A week after it was written, this letter was read at the meeting of the Royal Society on April 6/16, 1687 (O.S./N.S. Birch's History, vol. IV p. 530, 531, 533. 534):

A letter of Mr. Leeuwenhoeck, dated at Delft, April 4, 1687, N. S. concerning the structure of the teeth, was produced and ordered to be translated againft the next meeting.

The following week, they read the first part of the letter.

Part of Mr. Leeuwenhoeck's letter of April 4, N. S. was read concerning the structure of the teeth, which he found from microscopical observations in all animals to be made up of bony vessels and pipes, which all take their rise from the inside or cavity of the teeth; and that all these vessels have their particular blood-vessels, that feed them, and convey nourishment to them. And the obstruction of these bony pipes he conceived to be the cause of the rotting of the teeth and the exceedingly acute pain of the tooth-ach. The rest of the letter was ordered to be translated.

And two weeks after that, the rest of the letter:

The latter part of Mr. Leeuwenhoeck's letter of the 4th of April was read, wherein he farther prosecuted the inquiry into the make of the teeth of several animals.

At the end of that meeting, the discussion returned to Leeuwenhoek.

It was ordered, that it be inquired of Mr. Leeuwenhoeck, whether he could discover any animalcule in the cicatricula of an egg; and that he be desired to inform the Society about what time of the year he made his observations, of the liquor of oisters being full of animals.

At the beginning of this letter, Leeuwenhoek followed up on Edmond Halley's request for his portrait.

I have duly received Your Honours' most obliging and agreeable letter of the 14th of February 1686/7 (and, since the one with Mr. Colson, no other), from which I saw that my Portraits were duly transmitted, as well as the Philosophical Transactions of last year. Further, Your Honours' missive is full of so many courteous remarks that I stand amazed, and wish to have the opportunity to be able to be of service to Your Honours.

All I would say in reply is that I was in no way displeased; and that what kept me from sending any observations, was because I had not received a reply, and now it appears from Your missive that one letter is missing. I herewith send you my modest Observations concerning some Teeth.

He had not written to the Royal Society for nine months. What had he been doing?

I have furthermore occupied myself, during the past winter, with preparing something of which I might avail myself in the future; I have not made any notes of the observations which I made thereof in the mean time; but at present I am engaged in examining several seeds that are sown annually for the benefit of the human race, and I will in due course despatch the same to Your Honours.

Specimens and methods: human teeth from the graveyard

In the text, Leeuwenhoek reported his observations of human teeth and compared them to horses' teeth. Where did he get these teeth?

I felt inclined to observe the structure of human teeth; and having obtained from a grave-digger (at my specific request) several big human teeth (which we call molars), I again saw, there too, that the same consist of no other parts but adjoining tubes.

After this I clove yet another tooth of that same horse, and very carefully removed all the salt that was in one of the four cavities of the tooth.


The original drawings are lost. The Dutch and Latin editions that Leeuwenhoek published had the five figures on the same three small plates placed within the text where he discussed them. The figures on the left sidebar came from the 1730 fourth edition of Continuatio Epistolarum. In the text, he noted that a local engraver drew them.

Now in order to put their structure before our eyes - as far as I was able - I have had part of two distinct teeth drawn.

Now in order to put before our eyes the thickness of the tubules of which the tooth is composed, I placed a small piece of the tooth before a magnifying glass, and handed that glass to a draughtsman (teijckenaer), and ordered him to draw whatever he might come to see (without the same knowing what he saw).

He ended the letter by mentioning the figures again.

I had ordered the draughtsman (who is also an engraver) to draw the accompanying fig: most accurately, whereupon he requested me to allow him to cut the same in copper, because they were not easy to draw in red chalk; and this, then, is the reason why I am sending a print of the same.

Since the drawings and print that Leeuwenhoek sent to London are lost, we can only speculate with figure or figures he referred to. In any event, this letter did not appear in Philosophical Transactions, so the Royal Society did not have to make another plate.

Other publications

While the Royal Society did not publish this letter in Philosophical Transactions, it was extracted twice in foreign journals, as were all the letters in Vervolg der Brieven, Letters 53 through 60. In the year after it was written, Jean Le Clerk published an excerpt, without any figures, in Bibliothèque universelle et historique, vol. 9, pp. 292-294.

In 1689, Otto Mencke pubished a short extract, again without figures, in Acta eruditorum, vol. 8, pp. 171-172.