Conducted an experiment with grapevines
Well before he began writing letters about what he saw through his microscopes, Leeuwenhoek was demonstrating his empirical mind. In this case, sometime around 1668 ("about twenty years" before 1688), he was trying to determine the difference between roots and branches, so he planted two shoots, one of them upside down. After several years, there was no difference between the plants that the shoots produced.
Letter L-199 109 [64] of 24th August, 1688 to the Royal society
About twenty years ago, I asked that a vine shoot of about three feet in length of a sort having very tasty fruit be put for me in the earth, in order that the shoot might strike root. This having been done, and when they were about to bring the layered young grapevine home to me, I asked them not to cut off the layered shoot close to the earth; to wit, that part which was attached to the stem.
Then, when this had been done, I took this young grapevine, which was rooted very well in the length of the shoot, cut it in the middle, where the roots lay, crosswise into two pieces, and I put both these young grapevines not far apart in the earth. This I did not only in order to have two grapevines, but in order to see what effect the one grapevine would have which would grow, and produce its shoots, the other way round. And after this grapevine had stood for two or three years, I could not find any difference in their growth; no more than later on in their bearing a good grape, and I still have them standing together today.
