fight-or-flight reaction The reaction in the body
when faced with a sudden and unexpected threat or
stress. The reaction is immediate to either run or stay
and fight. In humans, a sudden release of the hormones
epinephrine and norepinephrine increases blood flow
to the muscles and increases blood pressure. The result-
ing increase in muscle strength and mental ability pre-
pares the body for either reaction that is chosen. In
other animals such as the wood thrush (Hylocichla
mustelina), flight is preferred over fight.
filial generation (offspring generation) The succes-
sive generations of progeny in a controlled series of
crosses, beginning with two specific parents (the P gen-
eration), and intercrossing the progeny of each new
generation. F1 is the first offspring or filial generation
between any two parents, the first generation of
descent; F2 is the second (grandchildren); and so on.
filter feeding The filtering of suspended food parti-
cles from a water current by using gill rakers or similar
organs.
fingerprinting In genetics, the identification of multi-
ple specific alleles on a person’s DNA to produce a
unique identifier for that person; used in forensics. There
aresix steps to DNA fingerprinting. First the DNA must
be isolated and removed from the cells of the animal or
plant. Then special enzymes, called restriction enzymes,
are used to cut the DNA at specific places, and the DNA
aresorted by size. The DNA pieces are then transferred
to anylon sheet, which is then probed. The fingerprint is
generated by adding tagged probes to the nylon sheet,
and each probe sticks in only one or two specific places,
wherever the sequences match. The final DNA finger-
print is created by using several different probes, with
the resulting end product looking like a grocery store bar
code. DNA fingerprinting is increasingly being used in
criminal cases, and people have been freed from prison
based on DNA fingerprinting.
See alsoGALTON,SIR FRANCIS.
Finsen, Niels Ryberg(1860–1904) DanishPhysi-
cian Niels Ryberg Finsen was born on December 15,
1860, in the capital city Thorshavn in the Faroe Islands
(Denmark) to Johanne Fröman and Hannes Steingrim
Finsen, an Icelandic family that could trace its ancestry
back to the 10th century and occupied many of the
highest positions in the administration of the Faroe
Islands. He received his early education in schools at
Thorshavn and then at Herlufsholm in Denmark.
In 1882 Finsen went to Copenhagen to study
medicine. After taking his final examination in 1890, he
became prosector of anatomy at the University of Copen-
hagen until 1893. He continued with private tutoring of
medical students to make a moderate income.
By 1883 he was diagnosed with Pick’s disease,
characterized by progressive thickening of the connec-
tive tissue of certain membranes in the liver, the heart,
and the spleen, with long-term impairment of the func-
tions of these organs. He also developed symptoms of
heart trouble and ascites, and became more and more
of an invalid until finally during his last years he was
confined to a wheelchair. It did not prevent him from
making contributions to medicine.
He was instrumental in discovering the effects of
light—and in particular ultraviolet light (then called
red light)—as phototherapy against diseases such as
lupus vulgaris in 1893. In 1895 he made a great break-
through that established his international reputation by
introducing the revolutionary carbon-arc treatment
(Finsen’s therapy) of lupus. In 1896 he founded the Fin-
sen Medical Light Institute (now the Finsen Institute) in
Copenhagen.
He received the Nobel Prize in physiology or
medicine on December 10, 1903, for his work in treat-
ing diseases with light.
Among the many publications by Finsen, two are
especially noteworthy: Om Lysets Indvirkninger paa
Huden(On the effects of light on the skin) appeared in
1893, and the classical treatise Om Anvendelse i
Medicinen af koncentrerede kemiske Lysstraaler(The
use of concentrated chemical light rays in medicine)
was published in 1896. The results of much of his
research are contained in the communications pub-
lished by his institute. Finsen tried to combat his illness
in various ways, including keeping a diet poor in salt
during his last years. This led to his last publication, a
thorough study of En Ophobning af Salt i Organismen
(An accumulation of salt in the organism) in 1904.
In 1899 he became Knight of the Order of Dan-
nebrog, and a few years later the Silver Cross wasFinsen, Niels Ryberg 129