The San Francisco call., 1904-04-17
GleansngS of Science.

December 9, 1908, by the representa-
tives Of the powers, made considerable
changes in the regulations previously
sn force TO prevent the invasion and
propagation OF cholera and plague.
For instance, II abridged and even
suppressed quarantine, on conoiron
that there be a complete disintection
OF every vessel, her passengers, ere"
and cargo, and a complete destruction
OF all rats and mice on board. war on
rats on board ship, supervision OF yes
sels from that special point OF view
such Is the new orientation OF the mar
itime prophylaxis in regard 70 plague
There was time when the rats rem
dered service; in the days when drains
were unknown, and when the roads
served the double purpose OF highways
and places Of deposit for refuse. BY de-
vouring the refuse the rats, to certain
extent, protected the purity Of the at
mosphere and consequently the public
health. To-day when this part OF their
natural functions is no longer needed,
rats have no longer a ''raison d'etre,"
or at any rate they should be kept
within their native country.
II is interesting TO know, in fact,
that the rat is an immigrant-an in
vader~-and that Il comes from the East.
The two principal varieties, the black
and he brown rat, are Of foreign orr
gin and emanate from Asia The black
rat is the older and the smaller. 1t is
distinguished by its tail being longer
than its body. The brown rat On French
s'Surmulot'D has large, fat body and
q much shorter tail The black rat is
q field rat The brown rat, which lives
fn towns makes a war Of determination
upon II; therefore IL takes refuge in
the country having no chance OF exist
ing except out Of the reach Of its rival.
In the eighteenth century, according to
N. H de Varigny, there was only one
species Of rat-the black rat-which at
that period freQuented both town and
country. The brown rat arrived later.
The immigration Of the black rat ap-
pears to have dated from the fall OF
the Roman Empire, and II is believed
that the Crusades facilitated its dis
eemination in the West. II is described
s. the thirteenth century by Albertus
Magnus Once arrived in Europe, ii
quickly spread to all parts. thanks TO
commerce and navigation. Abo1t 1914
It made its way 10 America, and by
the middle OF the nineteenth century IT
at the same time spreading north and
south, 70 Texas and Canada 1t lived
and fiourished for a certain time, until
the brown rat arrived.
This variety also came from the
East. In an interesting article by NJ.
III. de Varigny, in the Temps, we are
told that Il made its appearance in Eu-
rope in the first half Of the eighteenth
century. For some unknown reason,
hordes OF these rats crossed the Volga
near Astrakhan. 1t has been supposed
that they were driven West by the fam
inc in India or by earthquakes in the
Caspian region. In 1850 brown rats in
vaded Russia, and also appeared in
Prussia: In 1870 they were brought TO
England by merchant vessels; in 1853
they took up their quarters in Paris.
Subsequently they invaded the other
countries Of Europe, passing into Den
mark in 1870 and Switzerland in 1903.
In certain parts OF Jutland they did not
appear until within fifty or sixty years
ago.
The brown rat" NJ. II. de Varigny
says. being larger. stronger and more
voracious, quickly turned out the black
rat. 1t starved its predecessor and de-
voured him as well. In the present day
the black rat is a rare curiosity, at any
rate IN cities; in country districts it is
still to be found. though in all cases it
disappears before the invasion OF the
brown rat"
The rat is in every respect a harmful
animal; il is an Unsuitable rodent, TO
which nothing eatable comes amiss
When hungry it viii even attack man;
and in certain badly-kept hospitals
rats have been known to have finished
of sick and feeble inmates.
Moreover. the rat is =. great traveller
The hold Of a ship is to him an earthly
paradise. He always finds goods there
and various kinds Of provisions. En-
barkation has no difficulties for him. He
works by night. when no one can place
obstacles in his way, and while the
ship is noored to the quay. He enters
by passing along the ropes, communi-
eating freely between the vessel and
the dock
Within the past few years another
element has complicated the situation.
The rat is not only the enemy of goods;
A. constitutes a serious danger TO the
public health. AS is now fully realized,
il is one of the principal agents in the
propagation OF plague. A victim OF the
disease which il propagates. II commu-
nicates the germs TO the feas from
which he received IL. The fleas bite
other rats or men. and infect them. and
thus plague is propagated. 1t thus hap
pens that a ship with all the appear
ance of perfect health on board may
be contaminated.
The passengers may be all right, says
NJ IL. de Narigny. but when the vessel
puts into a tainted port a rat enters
her along the mooring ropes. The rat
dies, but his fieas contaminate the rats
on board, and they in turn contaminate
the fleas, and the rats and fieas con-
veyed with the goods on board carry
plague with them. The recent case at
Marseilles and others elsewhere con-
clusively show how simple is the chain
Of events.
All these facts have shown the In
ternational Sanitary Commission that
IL was on the wrong tack when il at
tempted to combat plague by means
OF quarantine. What it ought to have
done was TO fight the rats. It is OF