Two variants of Levende Dierkens
We don't know who came up with the idea of publishing Leeuwenhoek's letters in Dutch. Nor do we know why Daniel van Gaesbeeck, a printer and bookseller in Leiden, issued the first batch of six in 1684. If fact, we don't even know which of the six was published first or who chose it, Leeuwenhoek, Gaesbeeck, or perhaps someone else. Why did Leeuwenhoek switch to Cornelius Boutesteyn, also in Leiden, for the batches of letters in 1685 and 1686?
The standard way of ordering them is Dobell's, which was chronological within each of the three years. The list below shows the date of the last letter in each, that is, the date before which the pamphets containing them could not have been printed and issued.
For the titles in 1684:
1. Onsigtbare Geschapene Waarheden, Letters 32, 33: November 12, 1680
2. Eyerstok, Letters 37, 39: September 17, 1683
3. Schobbens in de Mond, Letter 40: December 28, 1683
4. Humor Cristallinus, Letter 41: April 4, 1684
For the titles in 1685:
5. Onsigtbare Verborgentheden, Letters 38, 42, 43: January 5, 1685
6. Sout-figuren, Letters 44, 45: March 30, 1685
7. Zaden van Boomen, Letters 46, 47: October 12, 1685
In summary, 13 letters had been published in Dutch by the end of 1685: Letters 32, 33, and 37 through 47.
Around the time of his 53rd birthday, then, Leeuwenhoek found himself in an interesting situation. He had begun publishing the letters consecutively after Letter 39, and he even got Letter 38 in there in 1685. However, he had missed a few, seven, in fact. So in 1686, he both filled in the gaps and forged ahead with a pamplet that Dobell numbered 8, short title Levende Dierkens.
Levende Dierkens had these seven letters -- 28, 29, 30, 31, 34, 35, 36 -- in two groups, Letters 28 - 31 and Letters 34 - 36. Each group was separately paginated, 5-40 and 1-35, no doubt so they could be mixed with other such groups.
For example, the left sidebar shows two versions A and B. Both have Letters 28 - 31 but version A followed them with Letters 34 - 36 and version B followed them with Letter 45.
Comparison of page 40 shows two different typesettings and two different versions of the figure. The pamphlets themselves give help in answering why these two versions, which have identical titles pages, were both published by Boutesteyn in 1686.
Letter 45 was also the second letter in Dobell #6 Sout-figuren, first published in the previous year, 1685. Comparison of the version in this bundle of Levende Dierkens with the version in Sout-figuren shows that it is identical. In Sout-Figuren, it was paginated 41-76. As it happened, Letters 28 - 31 ended on pagre 40, so Letter 45 fit the numbering perfectly.
Thus by mid-1686, Leeuwenhoek had published all the letters between 28 and 47.
Throughout 1686, he kept busy with his microscope and produced letters in January and then once a month in April, May, June, and July. He published these five, Letters 48 - 52, in late 1686 (Dobell #9 Cinnaber Naturalis).
Leeuwenhoek must already have had a larger volume in mind, what turned out to be Werken Part I. It doesn't exist as a separate continuously paginated volume. It is, instead, any collection of these early letters in whatever order they were bound. The pagination in ten separate groups was condusive to shuffling the order.
For the opening pages of most of these bundles, the pamphlet with Letters 28 - 31, Leeuwenhoek included a frontispiece by Romein de Hooghe. De Hooghe, from Amsterdam, was a prominent and prolific artist whose signature at the bottom added gravitas to Leeuwenhoek's work. At the time, frontispieces were still competing with title pages for supremacy. This one repeated the most essential information from the title page it faced: "door Antoni van Leeuwenhoek" (by Antoni van Leeuwenhoek) at the bottom. However, it said "Ontdeckte Onsigtbaarheeden" (The Invisible Discovered) on the pedestal. The title page did not have those words and mentioned topics only in Letters 28 - 31. This frontis led off Dobell's edition of Werken, Part I (1932 p. 392):
Made up of Nos. 1, 2, 3, 4, 5, 6, 7, 8, 9: thus containing Letters 28-52. With engraved title dated 1685 (1st state, with Dutch lettering "Ontdeckte Onsigtbaar-heeden").
Of the few copies of Werken Part I that I have examined, none have the pamphlets in Dobell's numerical order, which is far out of chronological order. Several of the volumes listed in STCN say "letters bound in numerical order". For those volumes, Dobell's #8 Levende Dierkens would come first.