Wrote Letter XXXII of 1717-03-02 (AB 331) to Abraham Cornelis van Bleyswyck

Date:

March 2, 1717

Standard reference information

Cole's number:

222

AB/CL number:

331

AB/CL volume:

Text of the letter in the original Dutch and in English translation in Alle de Brieven / The Collected Letters is not yet available at the DBNL - De Digitale Bibliotheek voor de Nederlandse Letteren.

The original manuscript is lost.

Over the years, Leeuwenhoek had often examined the optic nerve in various animals, but he had not been able to examine other nerves in any detail. In this letter, Leeuwenhoek reported that he was finally able to examine nerves; he described the vessels and cavities in the nerves of the spinal cords of cows and sheep. He also observed the particles of fat between the nerves and membranes around the nerves.

Leeuwenhoek's summary

Inhoudsopgave, summary of the contents, for Send-Brieven XXXII. My translation and emphasis.

De zenuwen uyt het ruggemerg van koeyen en schapen gesneden en door het Vergroot-glas onderzocht. Dezelve bestaan uyt zeer dunne vaatjes. Het gepast van het samenstel der zenuwen kan de Auteur aan een ander niet mede deelen, en waarom: Honderde van vaatjes, die een zenuwe uytmaken. Holligheden in die vaatjes gezien. Hoe kleyn die holligheden zyn. Verheventheden, op de doorgesnedene zenuwen leggende, waar door veroorzaakt?

Opspraak, die de Auteur by onverstandige menschen lydt. Een zenuwe, die overdwars doorsneden was, afgetekent, en aan den Leezer vertoond. De strengen, waar uyt een zenuwe bestaat, en daar en boven de holligheyt van de zenuwe, ja zelfs de deelen waar mede de vaatjes gevult zyn, door het Vergroot-glas beschouwt. In yder strengstje van de zenuwe, als het overdwars doorsneden was, was een langachtig streepje te zien; 't welk niet anders was als de toegedrukte holligheden der vaatjes.

Die holligheden door eene figuur verbeeldt. Eene doorgesnede zenuwe van vyf andere zenuwen omvangen. Zenuwtjes met vet-deelen omzet. De zenuwen worden van malkander als gestooten door de vet-deelen. Sommige zenuwen zonder vet-deelen. Hoe de deelen van het Ruggemerg gestrekt leggen. De holligheden van de vaten des Ruggemergs waren by het daglicht te bekennen. De rok, waar mede het Ruggemerg bekleedt is, van een gescheyden. Veele dunne zenuwtjes, dicht by den anderen, uyt het Ruggemerg voortkomende. Groote dunte van die zenuwtjes.

De zenuwen, uyt het Ruggemerg voortkoomende, vestigen zich in de hoornachtige rok van het Ruggemerg. Uyt die rok schynen zy sterker voort te koomen; en schynen daar een dikker rok aangenomen te hebben. Eenige zenuwen uyt het Ruggemerg van een Koe overdwars doorsneden. En wederom bevonden dat de rokken der zelven van binnen bestaan uyt zulke lange deelen, als boven is gezeyt. Waarschynlyk was daar een vloeybarre stoffe in geweest.

De doorgesnedene deelen van zoo eene zenuwe afgetekend. In sommige zenuwen een holligheyt gesien: in andere was de holligheyt toegedrukt. De holligheden in de zenuwen noch klaarder gezien.

Nerves cut from the spine marrow of cows and sheep and examined through the magnifying glass. The same are composed of very thin little vessels. The appropriateness of the system of the nerves the author can not announce to another, and why: Hundreds of little vessels that make up the nerve. Cavities seen in the little vessels. How small the cavities are. Elevations, lying on the sliced nerve, caused by what?

Reproach that the author suffered from poorly ignorant people. A nerve, that was cut transversely, drawn, and shown to the reader. The strands that the nerves are composed of, there and above the cavity of the nerve, even the parts that the vessels fill, viewed through the magnifying glass. In each little strand of the nerve, when it was cut transversely, a long stripe was seen; which was not other than the closed cavities of the vessels.

The cavities represented by a figure. A cut-through nerve encompassing five other nerves. Little nerves with fat particles around them. The nerves are pushed away from each other by the fat parts. Some nerves without fat parts. How the parts of the spinal cord lay stretched. The cavities of the vessels of the spinal cord were detected by daylight. The skirt that also covers the spinal cord is separated from it. Many thin little nerves, close to the others, come out of the spinal cord. Great thinness of the little nerves.

The nerves, coming forth from the spinal cord, establish themselves in the horny coat of the spinal cord. They appear stronger coming forth from the coat and appear there to have acquired a thicker coat. Some nerves from the spinal cord of a cow cut transversely. And further found that the coats are themselves inside composed of such long parts, as was said above. Probably a liquid had been in there.

The sliced parts of such a nerve represented. in some nerves a cavity seen: in others the cavity was shut. The cavities of the nerves seen yet more clearly.

Specimens and methods

Some few years ago I also put down my discoveries on paper, but I have not attempted to look them up, although they were to hand, in order that these last discoveries of mine would not be mixed up with the earlier ones because I find again and again that the more I focus my thoughts and investigations ...

The edge of the knife, moreover, must be as sharp and thin as feasible, for else the little vessels are pressed together.

The public and their opinions

I know quite well that this writing of mine will not be accepted by some people because they judge that it is impossible to bring about the said discoveries. But I am not offended by such contradictions. Presently, it is also said about me by the ignorant that I am a magician and that I show people that which does not exist. But it may be forgiven them. They do not know better.

A certain gentleman said to me (some few weeks ago) that I should not sit idle in my old age, that the fruits that mature in the autumn may keep the longest.

I am not accustomed to send any discoveries or investigations to someone until they are completed. Yet because I was engaged on the investigation of the nerves, and because Your Honour, when being with me, said to me that I would not discover openings in the nerves, therefore I sent my notes and figures, both of which were not nearly completed, to Your Honour, with the thought that not only Your Honour would contemplate and read them, but that you would show them to the very clever and perspicacious gentleman.

When Your Honour handed my writing back to me, you told me that the gentleman just mentioned said to you: for what else than for little vessels would those little lines serve? and so Your Honour also comes to support me and accept the openings.

Now you should also reject the imagined egg nest [ovary] and accept my view of procreation through the animals in the male semen, just as very many gentlemen in other countries accept my theses.

Figures

Figures

The original drawings have been lost. The five figures are on one plate facing p. 316 in Send-Brieven and p. 312 in Epistolae Physiologicae. In Hoole, figures 1-3 are figs 37-39 on Plate XIX.

Related images:

Spinal cord of cow

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
1718	Leeuwenhoek, A. van	Send-Brieven
1719	Leeuwenhoek, A. van	Epistolae Physiologicae

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Period 6 - 1712-1719

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Wrote Letter XXXII of 1717-03-02 (AB 331) to Abraham Cornelis van Bleyswyck

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