Janicki born in Moscow (1876) lived in Warsaw up to graduation from high school (1893). Then he emigrated to the Western Europe for the next 25 years. Janicki had studied and curried out scientific researches in the field of helminthology and protozoology at universities and institutes in Germany, Switzerland and Italy. In 1918 Poland reagained independence and Konstanty Janicki returned from abroad to Warsaw. He was nominated as a professor and chairman of the Department of Systematic and Morphological Zoology at the Warsaw University. In helminthology Janicki was a world wide known discoverer of the life cycles Diphyllobothrium latum and Amphilina foliacea. In the protozoology the most important are the studies on the Metamonadina and Paramoeba (Janickina). During period 1919-1932 Janicki was surrounded by numerous students. Some completed Ph.D. under his guidance. He was main founder of the parasitology, protozoology and hydrobiology in the first half of the XX century in Poland.