His aristocratic father, Ivan Illitch Petrunkevitch, was a liberal member of the
First Duma and founded the
Constitutional Democratic Party. After finishing his studies in
Moscow and in
Freiburg under
August Weismann, Alexander settled in
Yale in 1910, becoming a full professor in 1917. Apart from describing present-day species, he was a major figure in the
study of fossil arachnids, including those in
amber and from the
Coal Measures. He also experimented with live specimens and worked on
insects. Petrunkevitch's formulation of the principle of plural effects (every cause is potentially capable of producing several effects) and the principle of the limits of possible oscillations (the number and the nature of the effects which actually take place may vary within definite limitations only) is well known, both in biology and psychology. Petrunkevitch was elected to the
National Academy of Sciences in 1954 and was also a member of the
Connecticut Academy of Arts and Sciences. Throughout his career he remained politically active, trying to increase awareness of problems in Russia. He was a founder, and later president, of the
Federation of Russian Organizations in the United States. He was also a skilled machinist and wrote two volumes of poetry (under the pseudonym Alexandr Jan-Ruban), and translated
Pushkin into the English language, and
Byron into Russian. He died in 1964. A 1917
portrait miniature of Petrunkevitch by
Margaret Foote Hawley is currently owned by the
Metropolitan Museum of Art. == Selected texts authored by Petrunkevitch ==