Professor Michał Siedlecki was a well-known Polish biologist and author of many scientific papers on marine zoology and biology. Together with Fritz Schaudinn, a German microbiologist, he conducted research on malaria. He was also one of the initiators of the construction of the Polish port in Gdynia. He was connected to the manor in Dołęga through his marriage to the daughter of the owners, Irena Wolska, as well as through his old friendship with her sister and last owner of the manor, Jadwiga Wolska Tumidajska. –Professor Siedlecki was a frequent guest at the Dołęga Manor House, where he also visited with the children from his second marriage, including his son Stanisław Siedlecki, a well-known geologist and polar explorer. In Siedlecki’s room an oil portrait of the professor– later the rector of Stefan Batory University in Vilnius – is displayed above the sofa. The portrait was made in 1921 by Benedykt Kubicki, a well-known portrait painter and long-time figure at Vilnius University who was professor at the Faculty of Fine Arts and the founder of the Department of Portrait Painting.