Savannah morning news. [volume] (Savannah) 1868-1887, 1883-10-30


In DIR. McKendrick's lecture before the
British Association it was shown, by pro-
/ jecting its image on screen, that the I'M
| injured frogs heart, isolated from the
body, still lives, and while beating gave
| with each beat an electrical variation, as
shown by the swing Of the galvanometer
needle. The uninjured heart gives no cur
rent, but when slightly injured there is a
! variation in it's electrical state with each
beat Then the lecturer showed that
| light causes an electrical change
| in the eye. Placing the eve
of a frog in the galYanometer
cushions, it was shown that there was a
current passing from the cornea to the
back of the eye. In the dark little or no
| change could be seen except what might
be due to the drying of the living struc-
lures forming the eye; on allowing light
to fall on the eye, there was at once an
increase in the current. This continued
for time, then began to fall off, and on
| light being removed there was another
I increase, and then a sudden and rapid
falling off. This action, first shown by
Professor Holmgren, Prof. Dewar and
the lecturer, showed a specific influence
of light on the retina. 1t could not be
| called a negative variation. 1t indicated
chemical changes occurring in
the retina. Lastly the lee
turer showed the production of cur
rents from the living man, Placing the
hands in two vulcanite troughs commune
eating by platinum plates with the gal
vanOmeter and filled with a-weak solution
of salt, he showed that on contracting one
arm a detection of the galvanometer
needle was produced. When both arms
were quiet there was no current; on con-
tracing one arm a current was at once
produced. This current, the lecturer was
inclined to think, was due to action of the
fluid on the skin and not to currents
from the muscles, and that the differences
were due to differences of contact. In
summing up, after few remarks regard
Ing electric fishes, the lecturer said that
/ all of these electrical changes were really
4 expressions of vital changes occurring
in living tissues under the action of
I stimuli. 1t was no part Of the functions
| of nerves, muscles, or of the retina of the
/ eye to produce currents under the action
/ of their relative stimuli, but such cur
rents indicated chemical changes in the
/ organs or tissues. For example, the con-
/ traction of a muscle is movement fol-
/ lowing or consequent upon many chemi-
/ cal changes, among the results of which
were the production of heat and differ
| ences of electrical potential. Thus there
was no special production of electricity,
except in the case of electrical fishes,
and possibly of some other animals.
In most animals, including man, the
! production of currents was an incidental
/ phenomenon, indicating chemical Ope-
ratiOns and nothing more. Besides,
! the currents so produced were
/ feeble and eVanscent, and bore no relation
| to the general well-being. Consequently
all attempts to influence the living body
by magnets had no rational basis. The
| lecturer had tested this question by pow
erful electromagnetic, and had not been
able to detect that they had the slightest
| influence on any vital phenomena. 1t
need hardly be added that the so-called
! phenomena of animal magnetism are of
an entirely different kind from those dis
cussed. These are of a subjective char
acter, dependent upon peculiar states OF
the nervous system, having nothing
whatever to do with electricity or
magnetism; but still in a sense they are
/ phenomena as real as those of physical
science. Their subjective character, how
ever, renders them specially difficult of
investigation, and consequently they are
more liable to fall into the hands of the
charlatan. One safeguard against this is
the recognition of what the electrical phe-
nOmena of the living body really mean,
and one purpose of this lecture will be
served if it shows that to detect and ac-
count for these phenomena requires the
most refined methods of the physicist and
of the Psychologist, ana that they give us
only a glimpse into the intricate changes
| occurring in living tissue.