Marble Hill press., 1915-01-28
HoRMoNEs.

Taken from tho Greek language
and meaning TO arouse or excite. the
word "hormones" is Intended TO desig-
nate a series OF chemical bodies man
nfactured within the cells OF one or
san and entering the circulation 10
excite or stimulate distant organs into
activity.
II has generally been Supposed that
the digestiva functions were carried
on solely under reflex nerve control.
But Edkius In 1906 carried out a Sc
ries OF experiments to determine
whether a chemical mechanism may
not also account for the secretion OF
gastric iaicc. which IL excited by the
introduction OF substances into the
stomach. In a series of carefully con-
troiled observations Il was proved that
the mere introduction OF a neutral So
luton into the stomach caused no Sc
cretion OF gastric Juice and that there
was no absorption OF the solution, the
Fluid removed at the end OF an hour
having the same bulk and the same
neatrai reaction as the solution orig
inally introduced.
The injection OF pep,one, OF acid. OF
broth. or OF dextrin into the blood
stream produced no secretion Of gas-
tric Juice. but II In the course o. the
hour during which the fluid was al
lowed to remaia In the stomach So
luton made by boiling mucous mem.
hrane from the pyloric end OF a stom-
aeh wtth water or with acid. or with
peptaue. was injected tnto the blood
stream al intervals OF about ten m!n'
ates. then the fluid withdrawn from
the stomach al the end OF the hour
vas found to be distinctly acid and 10
have protein digestive powers--that
IL 10 say. II now contained hydro
ehioric acid and pepsin.
Similar solutions made from the car
diac end OF the stomach viii not pro-
d0ce any secretion OF acid and pepsin,
and this Is held to prove that the
pyioric end OF the stomach produces Il
substance which is absorbed into the
blood stream and carried 10 all the
glands Of the stomach. where II acts
as specific excitant of their secre-
tory activity. This substance has been
called the gastric "secretin"-it is
what Startling named "hormone."
Normal gastric secretion appears to
be due 10 two cooperating factors.
The first and most important Is the
secretion arising from nerve impulses
produced through the pneumogassric
nerve and originating In the idea OF
food In the higher parts OF the brain.
from the sight OF food and by the
stimulating OF the mucous membranes
Of the mouth. The second factor pro-
vides for the continued secretion OF
gastric Juice long after the mental
effects have disappeared This Is
chemical and depends on the produc-
tion In the cells at the pyioric end OF
the stomach OF a specific stimulant or
hormoae. which being absorbed into
the blood is carried to all parts OF the
cerued In the digestive act
The researches OF Pawiow and 9th.
ers seem to indicate that the quantity
and the properties OF the secretions
vary with the character Of the food
eaten. The quantity OF the secretion
varies also. other conditions being the
same. with the amount Of food to be
digested.
On a given diet the secretion as
sumes certain characteristics and
Pawiow II convinced that further
work will disclose that the secretion
of the stomach Ia not caused normally
by general stimuli affecting II all alike
but hy opecific stimuli contained eth.
er In the food or produced during di.
gestiou from the food contents the
action Of which Is OF such kind as
to arouse refexly the secretion best
adapted to the particular food in
gested. Undoubtedly this Is due to
the hormones In the circulation.
Another significant hint of this ac-
tion Is furnished by the experiments
OF Startling and Lane-Ciaypon on the
mammary glands. These investiga-
tors found that the extracts made
from the body OF the fetus when In.
jected repeatedly into the blood
stream OF q virgin rabbit caused q
genuine development OF the mammary
glands. closely Stimulating the growth
that normally occurs during preg.
nancy. Similar extracts made from
ovaries, placentai and uterine tissues
had no such effect: hence. they con.
clude that q specific chemical sub
stance. hormone. h produced IN the
fetus itself which being absorbed into
the maternal blood acts upon the
gland. stimulating II to
growth
There h indisputable evidence OF
the existence Of similar bodies which
determine the secretory activity both