| Date | 1683 |
| Author | Leeuwenhoek |
| Contribution | a. Reported the presence of protozoa and bacteria in the feces of frogs. |
| Reference | Foster |
| Notes | Reported in Dutch, in a letter of 16 July 1683 (addressed to Sir Christopher Wren). Shortened English version published in 1684. See Dobell. The protozoa included what were probably Opalina, Nyctotherus and Trichomonas (or Trichomastix); see Dobell. Accompanied by drawings that strongly suggest that the organisms were what would later be called bacteria. About the same time Leeuwenhoek discovered microorganisms in scrapings of the tongue. Apparently he did not link them to disease, except to note more of them in people who had bad breath as a result of not cleaning their teeth. Bardell (1982) comments that this, the definitive discovery of bacteria, was reported by Leeuwenhoek 7 years after his first apparent observation of them (see 1676). His text and illustrations clearly show that he saw rod-shaped bacteria. His illustrations of round organisms are usually interpreted as depicting cocci or micrococci, but Bardell (1982) points out that examination of the text calls this into question, because the organisms were said to be fast-moving and changeable in shape. |
| Category | Miscellany |
| Pathogen Class | Bacteria |
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