Photo from Scientific Research

Ivan Pavlovs dogs and their caretakers in the grounds outside the Physiology Department of the Imperial Institute of Experimental Medicine, St. Petersburg, Russia. Credit: Wellcome Library, London. Wellcome Images[email protected];http://wellcomeimages.org. Photograph 1904 Published: [1904]. Copyrighted work available under Creative Commons Attribution only licence CC BY 4.0.

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