Annotations on the back read "Fig.3 Jefferson Descartes", "29528/5" and "47/05/35/07".
This image features as figure 3 in the publication, G. Jefferson, 'René Descartes on the localization of the soul', Irish Journal of Medical Science, 1949, 285, pp.691-706. The Purser lecture was delivered by Jefferson on 26 May 1949 at Trinity College, Dublin. The description of the image given in the article is as follows: "The rows of circles are the open ends of nerve tubes leaving the ventricles, impulses from the uncrossed (herbivorous chiasma crossing on to the pineal: observe the 'floating' pineal gland".