Compound eye of a beetle (fig 1-4) and trachea from brain of a gnat (fig 5).
fig. 1 cornea; figs 2-4 ommatida.
unknown draughtsman of Antoni van Leeuwenhoek
The collected letters of Antoni van Leeuwenhoek. Part XII, 1989, <a href="//commons.wikimedia.org/wiki/Special:BookSources/9026508956" title="Special:BookSources/9026508956">ISBN 9026508956</a>