Evening star., 1930-12-11
GLAND VARIANCE
HELD HEREDITARY
Carnegie Institution .Geneti-
CiSts Trace Characteristics
due to Pituitary Body.
BY THOMAS R. HENRY.


Minute differences in some of TIT
glands of Intervals secretion are trans
mitted by heredity.
Convincing evidence to this effect
with far-reaching implications as to th'
still mysterious origin of races Of mer
and animals, has been obtained by th'
Department of Genetics of the Carnegie
Institution of Washington.
The first witnesses are a cageful o
dwarf mice. They belong to a specie!
the normal individual of which weigh!
about 40 grams when full-grown. Blu
these mice, born of normal size, stoY
soon as they begin eating solid food
Just such dwarf is born in a human
family now and then.
Have Defective Glands.
Examination shows that the dwarf
mice have defective thyroid and adrena
glands. Most serious of all, the from
lobe of the tiny pituitary gland at tht
base of the brain is under developed
This is known to secrete into the blood.
stream infinitestimable amount of two
complex chemicals, which have not yei
been isolated. A deficiency of one cause:
O condition that prevents growth.
The parents of these dwarfs appear
TO be normal. but it has been demon
strated that they always are of speci-
f1c hereditary strain. The growth
stopping complex of factors, in which
Secretions of other endocrine glands are
supposed to enter, appears to work as q
unit transmitted approximately accord
ing to the Mendelian law of heredity.
That this hereditary unit works
through the channel of the endocrine
glands has been demonstrated by Prof
Philip E. Smith of the College of Ply
sicians and Surgeons Of New York, in
cooperation with the Department of
Genetics. For if the anterior lobe of
the pituitary gland is replaced surgi-
cally the mouse will grow normally and
breed. A preparation of the whole
lobe is injected into the leg muscles.
This SHOWS that this gland has the
power of regulation over the other
growth glands. All are in
timately tied together in the mechanics
OF the living body. Everything follows
from slight defect in a single one of
these mysterious organs.
Ratio Is Fixed.
Experiments have shown that a quar-
ter of the offspring of two dwarf-pro-
ducing parents will be dwarfs. half will
be dwarf-producing normalS and a
quarter will be normalS that will not
produce dwarfs. This indicates that
the mechanism which produces dwarf
ness, probably extremely complex, Is
due primarily to a single hereditary
unit which may be transmitted in q
latent condition by normal mice. 1t
is a "recessive" unit in the terminology
of the geneticists. This supposes q
dominant unit necessary for the normal
development of the anterior pituitary
lobe
Now human dwarfs also are due to
anterior lobe deficiencies The expert
ments with mice strongly indicate that
the human conditions also is hereditary,
The chemical substance secreted is eX-
tremely powerful and specific. The fact
that the mice can be restored to normal
by the injection of the macerated lobe
itself holds out the hope, 1t is pointed
out, that this method may cure dwarf
ism in man with further DEVELOPMENT.
With the mice daily injections of ex-
tremely slight amounts are made
There Is no building up of a supply oi
anterior lobe hormone In this respect
the macerated preparation is in the
same category with thyroxin, the syn
thetically produced hormone which ir
nature Is secreted by the thyroid gland
Deficiency Of this thyroid secretion leeds
to a condition Of stunted growth anC
feeble-mindedness known as cretinism
which a few years ago was hopeless
But victims now can be restored Il
normal and kept there indefinitely b,
q daily dose Of the synthetic product.
Having proved a hereditary condi-
ton due to pituitary deficiency in mice
the Carnegie experimenters leave oper
the question as to the origin of sucf
dwarf human races as the African
and Melanesian pygmies. Dwarfness In
the mice is not transmittable by ths
dwarfs themselves, since another hor.
none secreted by the anterior pituitary
lobe Is essential to reproduction. Nc