The Krieger collection, comprising 12,482 glass plate negatives made in the years 1880-1926, has been stored from 1968 in the Historical Museum of the City of Cracow. Among 5,414 glass negatives examined, 20 were found to be contaminated by fungal growth. Among 13 species of fungi <i>Aspergillus nidulans</i>, <i>A. versicolor</i>, <i>Cladosporium cladosporioides</i>, <i>Penicillium cyclopium</i> and <i>P. janthinellum</i> were the most frequent. At 63% relative humidity a scarcely visible growth was confirmed, on shellac and collodion, but not on dammar.