?100	REPORT OF THE LEPROSY COMMISSION:
Modern bacteriological research has disclosed many facts which
clearly indicate that contagiousness is an extremely relative
term. This will be more fully considered subsequently, and
here only a few points will be mentioned in proof of how easily
general causes, such as poverty, famine, and precarious living
may lead to a special disposition towards a disease-may, in
fact, cause such disease to be endemic over a certain area.
It has been shown that dogs of one colour are more susceptible
to anthrax than those of another; pigeons and hens, normally
resistant against the same disease, are easily infected, if allow-
ed to starve. Again rabbits, naturally more or less refractory
to quarter evil, lose their immunity through fatigue and over-
exertion; and Hankin has shown that a meat diet increases the
resistance of ordinary rats against anthrax, while a milk diet
causes them to be susceptible to this disease. These few
facts-and instances might easily be multiplied-show how
readily a disease, originally non-contagious for a certain class
of animals, may be rendered contagious. The virus has re-
mained unchanged all the time, but an alteration in the
organism of the individual has taken place.
 An endemic area, then, would be one where (a) the virus
in some form or other is present, and where also (b) such
conditions exist as are calculated to exercise a special pre-
disposing influence on the population, thus enabling the para-
site not only to enter the body but also to grow and thrive in
the same. It has been seen that there are districts in India
where leprosy is exceedingly prevalent, and has been so at all
three enumerations. These districts agree chiefly in the follow-
ing points, viz., the existence of poverty, insanitary conditions,
over-population, unhealthy or moist climate. Whether the virus
is also abundant in these districts cannot be proven, so long as
bacteriology is almost ignorant regarding the life history of the
leprosy bacillus. As the disease has existed in India since
antiquity, it is highly probable that the bacilli in a resting
stage are widely distributed, ready to encounter the susceptible