Capillaries from a tadpole.
<p>fig 3 with free erthrocytes (X). 
</p>
fig 5 Tadpole
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>