(b. Cracow, Poland, 1873; d. Sachsenhausen. Germany./January 1940)
Siedlecki was born into a middle-class family. He studied at Jagiellonian Cracow University at Cracow and received the M.D. in 1895. The following year he went to Berlin to work with Schulze, whose assistant at that time was Schaudinn. From 1897 to 1899 Siedlecki worked at the Pasteur Institute under Metchnikoff and also at the Zoological Station in Naples under Anton Dohrn.
Siedlecki’s first paper dealt with leukocytes of Urodela (1895). He later studied the phagocytes of Annelida (1903) and, with Caullery, Echinodermata (1903). With Kostanecki, he published an interesting paper on the cytology of Ascaris. In 1908–1909, Siedlecki went to Java, where he became interested in frogs of the genus Rhacophorus and in fishes and birds.
Siedlecki’s outstanding scientific contributions, however, were in protozoology, which he first studied at Schulze’s laboratory. When Sieldeckiwent there he intended to work under Schaudinn on Foraminifera. But Schaudinn was also interested in the life histories of Sporozoa and suggested to Siedlecki that they work together in this area, studying the Coccidia of Lithobius forficatus. In a joint, preliminary paper (1897), they described the life histories of Coccidium schneideri and Adeleaovata. This paper, a classic in protozoology, was the first to describe correctly the life cycle of Coccidia. Siedlecki’s trip to Naples and Schaudinn’s military obligations prevented them from publishing the full results of their researches.
Siedlecki was the first (1898) to describe the sexual cycle of Klossia octospina (or Aggregata eberthi) in Sepia, the only known host until 1908, when Léger and Duboscq found an asexual cycle in Portunus. The following year he published the first complete life cycle of a gregarine (Adelea ovata) living in Lithobius forficatus.
In 1900 Siedlecki was appointed lecturer of zoology at Cracow and in 1912 professor and also director of the Zoological Laboratory and Museum. From 1919 to 1921 he was rector at the University of Vilna, helping to plan its reconstruction after World War I. Later he returned to Cracowg. He also served as the Polish representative to the Permanent Council for Marine Exploration and to the International Committee for Bird Preservation.
After the Nazi invasion of Poland, Siedlecki and many of his colleagues were arrested on charges of promoting Polish nationalism. He was jailed first at Cracow but was later transferred to a prison in Breslau, and finally to a concentration camp at Sachsenhausen-Oranienburg, where reportedly he died of heart failure and “ill treatment”
I. Orignial Works. Siedlecki’s works include “Beiträge zur Kenntnis der Coccidien,” in Verhandlungen der Deutschen zoologischen Gesellschaft, 7 (1897). 192–203, written with F. Schaudinn: “Étude cytologique et cycle évolutif de la coccidie de la seiche, “in Annales de l’institut Pasteur, 12 (1898), 799–836: and “Étude cytologiquee et cycle évolutif de Adelea ovata Schneider, “ibid., 13 (1898), 169–192.
II. Secondary Literature. On Siedlecki and his work, see “Michael Siedlecki, “in Nature, 145 (22 June 1940), 963; “Michael Siedlecki, “in Zoological poloniae4 (1948), 51: and Clifford Dobell, “Michal Siedlecki (1873–1940),” in Parasitology33 (1941), 1–7.