In the attempt to understand epidermal sensitivity (eczema) in man, it is only natural that fundamental studies should have first been carried out with a favorite laboratory animal, the guinea-pig.
A review of the literature reveals that Bloch1 was the first investigator to succeed in producing eczema (epidermal sensitization) in the guinea-pig. He and his co-workers found that when a small area of the skin was abraded and painted with primula extract, both local and general epidermal sensitivity appeared later.
After Bloch's experiments a number of investigators have reported studies on sensitization of guinea-pigs to paraphenylenediamine, and the studies of Landsteiner and Jacobs2 stand out, perhaps, as the most illuminating. In the laboratory of the Rockefeller Institute these experimenters found that by repeated intracutaneous inoculation or repeated inunction of guinea-pigs with a number of simple compounds they obtained cutaneous sensitization which was easily reproducible. Positive effects were obtained