In 1927, we1 reported on the preparation of lens extract and its crystalline fractions. In more recent papers2 we have gone into further detail concerning the preparation and purification of these fractions. No mention has been made of the use of lens extract, either as a therapeutic or as a diagnostic agent, although it has previously been used by several other workers. Römer3 used lens extract by mouth, and Davis4 by subcutaneous injection, as a therapeutic agent in the treatment for cataract. In 1922, Verhoeff and Lemoine5 described endophthalmitis phaco-anaphylactica, and announced the indications for treatment with lens protein for this specific condition. Their conclusions were later sharply challenged by Rotth,6 and these objections were later replied to by Verhoeff. Berens and his co-workers7 reported observations on several patients with hypersensitivity to lens extract who were treated by injections of such extract