The Richmond Virginian. (Richmond, Va.) 1910-1920, 1914-04-01

the puzzle. and il baff1ed the Indian
Plague Research commission and
many other scientific workers all over
the world for nearly decade.
Problem II Solved.
The problem has been solved by
A. w. Bacot, entomologist to the Lis
ter institute. and DR.. c. j. Martin,
who, with an ADVISOR committee Of
which he is a member has exercised
general control over the work of the
commission. Many men study insects.
but Mr.. Bacot breeds them For
long time he and DR.. Martin studied
at the Lister institute the mechanism
Of the transmission Of plague by the
fieas. At length they noticed. with
some surprise, that although certain
plague infected fleas sucked vfgor-
ously at the shaven abdomen or rats,
no blood entered their stomachs.
the mystery.
1t was found that when plague
germs enter the stomach OF flea
they soon form solid jellylike masses
of bacterial culture. A flea, like
many other insects. has at the open
ing of its stomach a wonderfully con-
trived chamber called the proventric-
ulus, a sort Of valve covered with
toothlike cells which closes during
the process of digestion. What hap
pens is that the jellylike Jumps of
germs drift forward from the stom-
ach into this chamber and I'LL 1t up
completely. The valve Is choked,
and no food can pass into the stom
ach. The wretched flea gets thirsty
and tries in vain to satisfy its crav-
ings. II sucks and sucks, but only
succeeds in distending with blood
what for simplicity we may call its
outlet.
The way to the stomach is blocked.
The fiea's frantic efforts drive some
OF the plague germs forward from
the valve chamber into the outlet.
When 1t relaxes some of the blood
IL has sucked surges back by recoil
from it's gullet into the puncture made
in the man or the rat: but the blood
has become infected. and on its re-
turn carries plague germs with It.
Such is the simple explanation of the
process which has perplexed experts
for so long; but 1t has required a
vast amount Of minute investigation
to prove it beyond doubt.
Much Doubt Cleared Up.
The theory of reorganization. which
was first speculatively advanced long
ago. is. in fact. the true one. Its
final discovery clears up several other
doubtful points. Thus it was believed
that a plague infected flea underwent
a cleansing process after certain
number OF days. and If it did not
again bite an infected rat became
free Of the plague germs. 1t is now
found that the belief is only partly
correct. The flea does after a time
dispose OF Its Jumps Of bacterial
culture by autodigestion. and the way
to its stomach may possibly become
cleared: but the process OF obstruc-
ton Is liable to recur, and on the
whole heas once infected have very
little prospect of future happiness.
In a cool. damp atmosphere 1t may
live long time, but heat soon kills
a starving flea with it's outlet plugged
up. Deprived OF fresh fluid. the in
sect quickly shriveIs in hot. dry
climate. Thus, it is believed. We
know at last exactly why In nothern
and central India plague epidemics
abruptly cease when the hot weather
begins.
How, then. does 1t reappear again
next cold weather? There Ia much
still to learn on that point, but the
PROBABILITY lS tHdi IL AHBSTS uuTiAS
the hot months among rats and fieas
below ground The fieas are fewer;
the rat mortality Is much smaller and
not visible above ground; but when
favorable conditions recur plague
may blaze up again. and in due course
the thirsty infected fieas bite human
beings as the rats die Off. An epidem-
ic among rats invariably precedes
by weeks. an epidemic |
among human beingA