22
has so short a life apart from its proper host, especially if it be infected
with plague, that 'anti-flea' measures received no specific mention.
Such measures will be referred to when (b) is under detailed consi-
deration : they have very decided value and should in no wise be
overlooked.
I.—EAT ELIMINATION.
A full knowledge of the habits and customs of the rat is essential
to the successful prosecution of anti-plague measures.
1. The rat.— The common Indian house rat, Mus rattus, is a very
domesticated animal and is rarely found far from human habitation.
For shelter it seeks the darkest corners of the dwelling, especially if
such offer facilities for burrowing and a convenient supply of food.
Such dark corners are to be found in almost any Indian dwelling.
The rat possesses remarkable powers of climbing, and the ordinary
kutcha mud wall offers no difficulties. A hard, smooth vertical surface
free from irregularities and projections is not easily surmounted. A
water-pipe or a drain-pipe which can be grasped by the rat's legs and
tail is easily climbed. A ledge, projecting horizontally nine inches
or more from the wall, if quite smooth and hard on the under surface,
presents an insurmountable obstacle. A rat may succeed in jumping
on to a ledge 2½ feet high but not one 3 feet high.
Grain is the natural food of Mus rattus, which is very largely
vegetarian in its habit : in certain circumstances the house rat will
devour 'meat' or even the dead bodies of other rats, but uncooked
grain is their chief article of diet. The variety of grain that is most
attractive to rats differs in different parts of the country, but the rats
of any given locality are remarkably conservative. Usually the rat
favours that variety of grain which forms the staple food of the human
population among which it dwells. Thus the rats of Poona prefer
bajri to anything else ; the rats of Madras are rice-eaters; the rats of
Sholapur affect an equal preference for jowari and bajri. Very
remarkable, too, is the facility with which the rat is able to identify
dough made from the flour of the grain to which it is accustomed
when several varieties are offered in exactly similar forra. The
addition of such substances as meat, fish, cheese, sugar, fats, condi-
ments or salt, as a flavouring to dough made of flour and water, does
not in any way render the mixture more palatable or attractive to the
rat. This statement is at variance with commonly accepted notions
and many will find it difficult to credit that a rat has no very great
partiality for cheese, for example. Nevertheless the above statement
is based on the results of numerous controlled observations designed
to determino this special point. It is not contended that rats won't
eat such substances as those enumerated above; at times they will
eat almost anything; nevertheless they exhibit universally a pre-
ference for grain, or flour made from grain in the form of a paste, in
preference to all else, and they like it best unflavoured. Finally, rats
must have water if their food be dry ; sufficient water is obtainable
from fresh, or wet, vegetables or grass.
A rat becomes sexually mature at a little over two months ; the
most common number of young at a litter is five. The sexes closely