Microscopium, or some new discoveries made with and concerning microscopes. Lectures and Collections made by Robert Hooke, Secretary of the Royal Society, pages 81-112.

On his title page Hooke listed the contents of this section as follows:

"Mr. Leeuwenhoeck's two letters concerning some late microscopical discoveries.
"The author's discourse and description of microscopes, improved for discerning the nature and texture of bodies.
"P. Cherubine's accusations answered.
"Mr. Young's letter containing several anatomical observations."

Digital facsimile from Google Books at this link.