Two images on one negative: the first is a reproduction of a half-tone engraving of Hipólito Ruiz López (1754-1816 in Madrid), Spanish botanist known for researching the floras of Peru and Chile during an expedition under Carlos III from 1777 to 1788. Signed "Hipólito Ruiz" underneath portrait. The second is a halftone reproduction of a portrait with the lettering "Francisco José de Caldas" underneath. The portraits were possibly reproduced as part of the exhibition Malaria section of the international celebration and exhibition : three hundredth anniversary of the first recognized use of cinchona by Europeans, 1630-1930 hosted by the Wellcome Historical Medical Museum in 1930. The portraits are possibly listed as exhibit no. 942 in the souvenir catalogue, and are not held by Wellcome Collection.