116v: the "plummeting stone"

[MarcoP]

The dots are amazingly fine compared to the regular penwork.

It may be a silly question, but could someone used to calligraphy explain how they were made?
I should think that with a quill any attempt to "dab" the nib would have created a larger ink blot.
Are we sure we're not just looking at some sort of strange ink blot?

They do look small, when compared with the thickness of characters, but the dot above the i of mich seems comparable to me.