Karel Dežman’s research of the karst phenomena was examined. Among his works the cave research, description of Proteus, other cave animals and plants were found. A special concern was put on Dežman’s sources dealing with Proteus research. As the custodian of the Land Museum of Ljubljana, Dežman promoted the Ljubljanian natural history research of his time. His scientific works are not very well known because he did not follow the political line of the official Slovenian national representatives.