# Degree of Ossification of a Five-Month-Old Fetus (Degré d'ossification d'un Foetus de cinq mois)

- By: Léon Tissier (French, 19th century)
- Date: 1898
- Medium: Gelatin silver print with applied india ink or watercolor
- Classification: Photograph
- Dimensions: Image/paper: 31.5 × 23.3 cm (12 7/16 × 9 3/16 in.)
- Culture: France
- Credit line: The Mary and Leigh Block Endowment Fund
- Museum: [Art Institute of Chicago](https://www.artic.edu/artworks/147149)
- Rights: [Public domain (CC0)](https://creativecommons.org/publicdomain/zero/1.0/)
- Picture: https://www.artic.edu/iiif/2/c240af34-6976-b596-77dc-8b46afd6af5a/full/!1920,1080/0/default.jpg
- Who can see it: Tweens profiles and older (museums give no ratings; placed by Invisible Network from the museum's own words)

In late 1895, physicist Wilhelm Conrad Röntgen inadvertently discovered a form of radiation that exposed photographic plates; as electromagnetic waves passed through opaque materials, they left behind shadowy images. He termed them X-rays, and news of the discovery spread rapidly. For the scientific community, X-rays expanded medical possibilities, allowing doctors to see interior anatomy without surgery. For the general public, these pictures spectacularly revealed places normally invisible to the human eye and became objects of enduring fascination. This X-ray appeared on the cover of Les Rayons X, a journal of radiology, on March 5, 1898, just two years after Röntgen's discovery. The accompanying article claimed that X-rays were "interesting and useful for the study of fetal development at all stages of pregnancy," describing in wonderment what can be seen clearly in the image (larger bones and the spine) and what cannot (connective tissue and cartilage).

Description © Art Institute of Chicago, CC BY 4.0