Nissen calls for the frontispiece, 2 engraved titles and 70 plates whilst the Norman copy has one engraved half title and 68 plates but does not mention a frontispiece. Buonanni, a jesuit and pupil of Athanasius Kircher, constructed his own compound microscopes for use in scientific investigations. Observationes defends his theories of spontaneous generation which had first been put forward in his Ricreazione dell'occhio e della menta (1681) and had been attacked by Redi for the methodological errors present in his work.

The Micrographia curiosa includes interesting observations on early microscopes and gives a precise description of the author's own model.