Evening star. [volume] (Washington, D.C.) 1854-1972, 1892-10-29

examine. Under the microscope the blood
coursing through the veins Of the foot affords Q
very interesting sixht.
Mr. Frog is fortunate II he gets of 90 easily.
The bioiosist 10 very likely to cut open his
stomach and draw out for exsmination A foid
OF the membranc which incloses the intestines.
For this purpose the fold il pinned down to
the board, when, from the scientific point Of
view, u exhibits very beautiful spectacle be-
meath the microscope The membrane con-
tains the important blood vessels which con-
yey the assimilated portions OF the food from
the stomach to the liver. In the veins the red
corpuseies can be seen tumblinR along in Q
continuous stream like stones In a torrent.
AFTER such an operation it would be quite pos
sible to preserve the life Of the victim bv anti
septic treatment, sewing up its Abdominal vail
Notning OF the kind is done. however, frogs
lives not being valuable enough 10 warrant the
trouble.
Sometimes the cerebral hemispheres. which
are the tninking part OF the BRAIN are removed,
whereupon Mr.. Frog becomes q mere living
automaton. In such condition he NAV live
Tor months, never moving except when touched
and taking food only when IL IL mt into his
mouth The>meehanicai functions of his mind
are still active but they only respond to irrita-
uon. similar reflex action is shown by the
muscles OF severed frogs leg. which contract
when irritated. II will be remembered that the
discovery OF galvanism was due TO this circum-
stance. Galvan WAS cooking some FROM iecr
for his sick wife in his laboratory, and an elee-
trio wire coming accidentally into contact with
one ofthem set 1t q dancing The development
of the frog is fayorite study for classes In
biology at the universities. The eggs are easily
obtainedfn spring and are so big that they can
be observed to advantage with an ordinary
pocket lens. Queerly enough, the whole mass Of
each egg is transformed into the tadpole. which
is not hatched out OF she'll like fish The
curious mctaniorphosis Of the tadpcle into the
frog is attributed 10 the supposed fact that the
ancestors of the frog were fish-like creatures,
some Of which acquired a habit Of living on
land lost their gills aad developed lungs,
Finally they became regular frogs, though re-
manning addicted to an aquatic life, and to this
day reverting at the beginning of their lives to
their ancient form.
One Of the finest biological laboratories in
the world is that Of the Johns Hopkins Uni
versity in Baltimore. Much vivisecting work
is done there. The institution uses for this
purpose about 500 frogs annually, which are
obtained from the Chesapeake, where they are
bred for market in ponds. The dogs and cats
employed are Migrants. supplied by enterpris-
ing boys, who receive 40 cents each for dogs
and IS cents apiece for cats. Rabbits and
guinea pigs are bought from fanciers and
pigeons are got from poultry dealers. A very
remarkable apparatus has recently been util-
lied in this laboratory for experiments relating
to the heart. II is simply glass box in which
the air Is kept at temperature Of 100
degrees. A dog is chloroformed SO that il cam
not move or feel pain. II ia put into the box,
and its mouth is connected with afr pump.
which keeps up artificial respiration while the
thorax Of the animal IL cut open, so that the
heart can be seen beating. The arteries going
to and away from the heart are then cut and
connected with bottles of sleeps blood.
which has been so treated that il will
not coagulate. Thus isolated from the
circulatory system the heart continues to
hpa tat sn a
forcing it into another. The nervous system
of the dog supplies motive power to the heart.
which is simply a pumping muscle. the connec-
ton of the nerves with the heart being uu-
disturbed. Now. il is possible to introduce
into the bottles any drug. and machine makes
automatic record OF the rapidity and fullness of
the heart beats. Thus it is practicable to dis
cover precisely what effects are produced on
the action Of the heart By various medicines.
knowledge Of these effects is very important to
medical science, and likely therefore to be Of
the greatest use for preserving human health
and life. For this reason such experiments
which would otherwise seem cruel and horrible,
are deemed warrantable. RENE BAcHE.