genetic variation; condition in which heterozygotes
have higher fitness than homozygotes.
heterozygous Two different alleles of a particular
gene present within the same cell; a diploid individual
having different alleles of one or more genes producing
gametes of different genotypes.
Heymans, Corneille Jean-François (1892–1968)
BelgianPhysiologist Corneille Jean-François Heymans
was born in Ghent, Belgium, on March 28, 1892, to
J. F. Heymans, a former professor of pharmacology and
rector of the University of Ghent, and who founded the
J. F. Heymans Institute of Pharmacology and Therapeu-
tics at the same university.
Corneille received his secondary education at the
St. Lievens College (Ghent), St. Jozefs College (Turn-
hout), and St. Barbara College (Ghent). He pursued his
medical education at the University of Ghent and
received a doctor’s degree in 1920. After graduation he
worked at various colleges until 1922, when he became
lecturer in pharmacodynamics at the University of
Ghent. In 1930 he succeeded his father as professor of
pharmacology and was appointed head of the depart-
ment of pharmacology, pharmacodynamics, and toxi-
cology; at the same time he became director of the J. F.
Heymans Institute, retiring in 1963.
His research was directed toward the physiology
and pharmacology of respiration, blood circulation,
metabolism, and pharmacological problems. He discov-
ered chemoreceptors in the cardio-aortic and carotid
sinus areas, and made contributions to knowledge of
arterial blood pressure and hypertension. He was award-
ed the Nobel Prize in physiology or medicine in 1938 for
his work on the regulatory effect of the cardio-aortic and
the carotid sinus areas in the regulation of respiration.
He wrote more than 800 scientific papers, was
active in a number of professional organizations, and
was publisher and editor-in-chief of the Archives Inter-
nationales de Pharmacodynamie et de Thérapie,found-
ed in 1895 by his father and Professor E. Gley in Paris.
He died on July 18, 1968, in Knokke.
hibernation A physiological state of dormancy, a
sleeplike condition, that lowers body temperature,
slows the heart and breathing, and reduces the need for
food for extended periods of time, usually during peri-
ods of cold. Examples of hibernators are bears, bats,
snakes, frogs, squirrels, turtles, and some birds.high-spin SeeLOW-SPIN.Hill, Archibald Vivian(1886–1977) BritishPhysiol-
ogist Archibald Vivian Hill was born in Bristol on
September 26, 1886. After an early education at Blun-
dell’s School, Tiverton, he entered Trinity College,
Cambridge, with scholarships. He studied mathematics
but was urged to go into physiology by one of his
teachers, Walter Morley Fletcher.
In 1909 he began study on the nature of muscular
contraction and the dependence of heat production on
the length of muscle fiber. From 1911 to 1914, until
the start of World War I, he continued his work on the
physiology of muscular contraction at Cambridge as
well as other studies on nerve impulse, hemoglobin,
and calorimetry.
In 1926 he was appointed the Royal Society’s
Foulerton research professor and was in charge of
the biophysics laboratory at University College until
1952.
His work on muscle function, especially the obser-
vation and measurement of thermal changes associated
with muscle function, was later extended to similar
studies on the mechanism of the passage of nerve
impulses. He coined the termoxygen debtto describe
the process of recovery after exercise.
He discovered and measured heat production asso-
ciated with nerve impulses and analyzed physical and
chemical changes associated with nerve excitation,
among other studies. In 1922 he won the Nobel Prize
in physiology or medicine (with Otto MEYERHOF) for
work on chemical and mechanical events in muscle
contraction such as the production of heat in muscles.
This research helped establish the origin of muscular
force in the breakdown of carbohydrates while forming
lactic acid in the muscle.
His important works include Muscular Activity
(1926), Muscular Movement in Man (1927), Living
Machinery (1927), The Ethical Dilemma of Science
and Other Writings(1960), and Traits and Trials in
Physiology(1965).Hill, Archibald Vivian 163