PROF. NICOLAI VICTOROVICH NASSONOV, who has recently died in Leningrad, was the oldest member of the Russian (now U.S.S.R.) Academy of Sciences. He was born at Moscow on February 27, 1855, and in 1874 entered the University of Moscow where he studied under the well-known zoologist, Prof. A. P. Bogdanov, and on obtaining his degree was appointed an assistant and later a lecturer at the Zoological Museum of the University. In 1889, Nassonov joined the University of Warsaw and a year later was appointed to the chair of zoology. In 1909 the Academy of Sciences elected him to membership and he was called to the post of the director of the Academy's Zoological Museum at St. Petersburg. A strenuous period of reorganizing the Museum occupied his time until 1921, when he became director of the Special Zoological Laboratory of the Academy which had been founded by the famous A. O. Kovalevsky. By 1925 this Laboratory, which at first occupied three rooms and had a staff of three men of science, had developed into a large Laboratory of Experimental Zoology and Animal Morphology. It was only in 1935, when eighty years of age, that N. V. Nassonov was persuaded by his medical advisers to retire from active administrative work, but even then he continued researches on regeneration until his death.