The collection presents the scientific output of Professor Marceli Nencki compiled by Nadezhda Sieber and Jan Zaleski. They have collected Professor Nencki's publications in two volumes entitled ‘Opera Omnia’, also including many works of his students, which were prepared in his laboratory and under his direct supervision. Due to the variety of topics and the wealth of material, the authors have decided to use an index, in which all works are arranged chronologically and according to their content. The collection of publications by the patron of the Institute of Experimental Biology was published in 1904. It presents the scientific output of Professor Marceli Nencki from the years 1869-1901.