Volume 1
Alle de brieven van Antoni van Leeuwenhoek / uitgegeven, geïllustreerd en van aanteekeningen voorzien door een Commissie van Nederlandsche geleerden.
- Antonie van Leeuwenhoek
- Date:
- 1939-
Licence: Public Domain Mark
Credit: Alle de brieven van Antoni van Leeuwenhoek / uitgegeven, geïllustreerd en van aanteekeningen voorzien door een Commissie van Nederlandsche geleerden. Source: Wellcome Collection.
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![[To Mr. C. Huygens, Seigneur of Zuylichem. Delft, April 24th, 1674. Very learned Sir, greetings, I received your kind letter of the 11th inst. in good order, and saw from it that my communications of the 5th were welcome to you. Also that you intended to send my observations to your son1) in France and wish to receive them personally. Urged by my curiosity and eagerness I have made further observations, which I take the liberty to send you. Having previously observed that blood consists of round, red globules floating in a crystalline fluid, I now examined it when very thin, its thickness not amounting to more than four or five globules. In this state the blood had very little colour2). This leads me to believe that the little veins — which permeate our body in great numbers, are white in colour, there being a great many of them, which I also distinguish in the thin, subtle membrane into which the flesh seems woven by means of some tiny tendons, and which the physicians call watervessels3) — not only are water- vessels but in reality also blood-vessels and that the crystalline blood4) can flow continuously through such small vessels or veins. I also believe that the red globules can only pass in one thickness and singly through some subtle veins. This being so one cannot 1) Christiaan Huygens. [H.] 2) The red blood-corpuscles, “which make the blood red”, are a light yellow, when seen separately. [H.] 3) L’s “watervessels” are lymphatic vessels. Their discovery was claimed by Thomas Bartholinus in 1653. L. evidently thinks that lymphatic vessels and bloodvessels are identical, but that they are colourless owing to their inconsiderable contents. This is a faulty opinion. [H.] 4) The crystalline blood: the clear part of the blood, the plasm (cf. note 1 to the letter of April 5th 1674). [H.] Red blood- corpuscles.](https://iiif.wellcomecollection.org/image/b31364962_0001_0091.jp2/full/800%2C/0/default.jpg)
