Ilya Ilyich Mechnikov was born on May 16, 1845, in a village near Kharkoff in Russia. As a
little boy, he was passionately interested in natural history, on which he used to give lectures
to his small brothers and to other children. He was at that time especially interested in botany
and geology. When he left school he went to the University of Kharkoff to study natural
sciences, and worked there so hard that he was able to complete the four year course in two
years. Thereafter he spent time studying marine fauna and later went on to do detailed
studies on the digestion of flatworms - work that had an influence on his later discoveries.
At work in St. Petersburg he met his first wife, Ludmilla Feodorovitch, who suffered from TB so severe that she
had to be carried to church in a chair for the wedding. For five years Mechnikov did all he could to save her life,
but she died on April 20, 1873. Broken by this loss, troubled by weak eyesight and heart troubles and by
difficulties in the University, Mechnikov became, at this time, so pessimistic that he tried to take his own life by
swallowing a large dose of opium; but, fortunately for himself and for the world, he did not die. It was in Odessa,
in fact, that he met his second wife, Olga, whom he married in 1875. In 1880 his second wife had a severe
attack of typhoid fever and, although she did not die, Mechnikov, whose health was still poor, again tried to take
his own life. This time, however, he decided, in order to save his wife and others embarrassment, to do this by
means of the scientific experiment of inoculating himself with relapsing fever to find out whether it was
transmissible by the blood. The attack of relapsing fever that followed was severe, but it did not kill him.
In 1882, after his recovery from this disease, Mechnikov went to Messina to continue his work on comparative
embryology, and it was here that he discovered the phenomenon of phagocytosis with which his name will
always be associated. This discovery was made when Mechnikov observed, in the larvae of starfishes, mobile
cells which might, he thought, serve as part of the defenses of these organisms. He tested the idea by
introducing into them small thorns from a tangerine tree which had been prepared as a Christmas tree for his
children. Next morning he found the thorns surrounded by the mobile cells, and, knowing that, when
inflammation occurs in animals which have a blood vascular system, leukocytes escape from their blood
vessels, it occurred to him that these leukocytes might take up and digest bacteria that get into the body.
Apart from its fundamental importance in immunology, the discovery had a marked influence on Mechnikov
himself. It completely changed his outlook on life; he abandoned his pessimistic philosophy and determined to
find further proof of his hypothesis.
Some proof of it he found in the small fresh-water Crustacean Daphnia, in which he found that fungal spores
which attacked it were themselves attacked by the phagocytes of the crustacean. He then studied anthrax bacilli
and found that the more virulent strains of these were not attacked by the phagocytes, while the less virulent
strains were. During this period Mechnikov took a job that required him to carry out Pasteur's vaccine treatment
of rabies, but there was much local hostility to this treatment. He found the job difficult and eventually went to
Paris to ask Pasteur for his advice. Pasteur gave him a laboratory and an appointment in the Pasteur Institute.
Here he remained for the rest of his life. At the Pasteur Institute in Paris Mechnikov was engaged in work
associated with the establishment of his theory of cellular immunity, which, like many great advances in science,
encountered considerable hostility. Nevertheless he persevered and published many papers on his work which
was eventually accepted as valid and extremely important. In 1908 he was awarded, together with Paul Ehrlich,
the Nobel Prize for Physiology or Medicine.
Mechnikov also showed that syphilis can be transmitted to monkeys. Later he took up the study
of the flora of the human intestine and developed a theory that senility is due to poisoning of the
body by the products of certain of these bacteria. To prevent the multiplication of these
organisms he proposed a diet containing milk fermented by bacilli which produce large
amounts of lactic acid and for a time this diet became widely popular!
Photographs taken of him when he was working at the Pasteur Institute show him with long hair and an unkempt
beard. It is said of him that at this time he usually wore overshoes in all weathers and carried an umbrella, his
pockets being overfull with scientific papers, and that he always wore the same hat, and often, when he was
excited, sat on it. From 1913 onwards Mechnikov began to suffer from heart attacks and, although he rallied for
a time and recovered from the distress which the 1914-1918 War caused him, he died on July 16, 1916.
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Biology 215, Ruth A. Gyure
Western CT State University
From Nobel Lectures, Physiology or Medicine 1901-1921; http://www.nobel.se/medicine/laureates/1908/mechnikov-bio.html
Biology 215, Ruth A. Gyure
Western CT State University