"I drank, one evening recently, about 2 pounds of good French wine."
In this letter more than many others, Leeuwenhoek had a range of concerns and specimens. In the manuscript, he divided the text into 13 marked and numbered sections, every time be began a new topic or set of specimens. When he had it printed in Zaden van Boomen and the various editions of Anatomia Seu Interiora Rerum, he did not retain these section marks and numbers.
He spoke of using a "magnifying glass" (vergrootglas), a "good magnifying glass" (goet vergrootglas), and "my most accurate magnifying glasses" (mijn naaukeurigste vergrootglasen).
His purpose was to find the beginning of a plant in every seed. After he did so in cotton, date-palm, clove, nutmeg, gooseberry, and black currant.
After this I have opened several other seeds, of which I will not give an account, as I think that it is sufficiently proven from these, and the preceding ones, that in each seed the beginning of the plant is made.
He restated the idea of a uniformity of processes and structures that he had spent years supporting:
Prudent nature achieves her ends, in nearly all cases, in one and the same way - as stated already many times heretofore.
And in addition to this my thoughts went out to the development of the scales (however small they may be) of which the outermost layer of our skin consists; for since we have seen that prudent nature, in all her workings, acts in almost exactly the same way, we are not to doubt, but must affirm, that the scales of our skin are likewise made from interweaving vessels.
Leeuwenhoek often used his own body as a source of specimens to examine.
During last summer, in the greatest heat, the outer skin of my hands was covered in many places with very many tiny blisters, many of which were no bigger than a coarse grain of sand. ...
I also examined, through a microscope, the surface of my skin where there were no blisters (after first wiping my skin dry), and I saw that, in a space which was no bigger than could be covered by a grain of sand, the sweat was oozing out very slowly, in quite 50 places.
What was the sweat made of? For example, if he drank something, would its microscopic parts end up in his sweat? He had recently examined wine and found a variety of what he called salts of different but unmistakable shapes.
Now when I had drunk, one evening recently, a quantity of about 2 pounds of good French wine, my body was a little upset by this, next day. And in the afternoon, I again drank about a pound and a half of good French, new Rhine-, and old Upper Moselle wine; and about two hours after drinking the last wine I drank a quantity of about a pound and a half of tea-water, as hot and as quickly as I could.
The hot tea would make him sweat.
While drinking the tea, I hardly took the cup away from my mouth at all; with this intention that I should be able, while inhaling through the nose, to draw in the hot, evaporating moisture into the windpipes, in order to make myself sweat all the more.
Then he examined the sweat.
I removed the sweat that broke out on my face as cleanly as I could; and on examining the same I observed that it was mixed with a large quantity of scales such as form the outermost skin, as well as an exceedingly large number of globules, which I judged to be one-sixth of a globule of blood in size.
He found other things, but not what he was looking for, salts from the wine.
I had no other intention in making the observations here described, than to find out whether I might not discover, in my sweat (which I had thus discharged with violence from my body), some salt particles of the wine, of which I had now been drinking an excessive amount in the space of fifteen hours.
However carefully I watched it, although I examined this sweat several times during three successive days, I was unable to discover therein the slightest trace of any salt particles such as are contained in the wines.
Later, the wine out of his body, he again examined his sweat and found that it was the same as it had been after he drank so much wine.
After this, when I was sweating profusely one afternoon, and had not drunk any wine that day, I again removed the sweat from my face; and on examining the same I saw an extremely large number of scales, as aforementioned, floating in it, as well as very many small globules.
The other time he used his own body, he wanted to confirm the uniformity of nature by showing that human skin scales are made from interweaving vessels.
I thought upon the scales in our mouth, as these are usually covered with moisture; and since I was busy, at about the time of these speculations, with the examination of a certain extraordinarily sharp fluid, it so happened that a few drops of the same accidentally got into my mouth. Although I spat it out at once, the upper layer of the skin in several places, particularly around my gums, had become so loose that I removed whole pieces of it.
On examining these parts I thought that not only had the scales, which constitute the outermost layer of skin, become detached from the skin, but I imagined being able to see that many vessels of the true skin.
Always the honest observer, in this case he had to finally give up.
But however much trouble I gave myself, I have not been able to satisfy myself about this latter question with certainty.