6
" Answer.—The assemblage in a lazaret, of persons coming from a place where
Cholera prevails, has not the effect of producing a great increase of the disease among
those in question ; but such an assemblage is, notwithstanding, very dangerous to the
neighbourhood, as it is likely to favor the propagation in it of Cholera.
" Question 23rd.—What influence have great assemblages of men, armies,
fairs, pilgrimages, &c, on the development and the propagation of Cholera ?
" Answer.—Great assemblages of men, (armies, fairs, pilgrimages,) are among
the most certain means of propagating Cholera ; they form great epidemic sources
which, whether the people march as an army or scatter themselves, as from fairs and
pilgrimages, carry the disease into the country they go through ; those assemblages
after having been subjected, in usually a rapid way, to the influence of Cholera, be-
come less susceptible of it, and the disease disappears from among them, it may be
even speedily, unless new arrivals come to prolong it.
" Question 24th.—What influence has dispersion on the intensity and the
development of epidemics of Cholera ?
" Answer.—The opportune dispersion of an assemblage may lessen the violence
of an epidemic of Cholera which has appeared in it, and may even prevent its spread-
ing ; but the dispersion would, on the contrary, cause great danger of propagation if it
took place in the midst of places as yet free from the disease.
" Question 25th.—What share has the pilgrimage to Mecca had, in the epide-
mics of Cholera that have followed one after another up to this time ?
" Answer.—The part borne by the Mecca pilgrimage, as an agent in propagat-
ing Cholera in the countries bordering on Europe, has been the importation of the
disease into Egypt twice, at an interval of thirty-four years, during the hot season.
" Question 26th.—What influence have the sanitary and other conditions
of a locality on the violence of an epidemic of Cholera ; in other words, what are the
adjuvant causes of cholera ?
" Answer.—Sanitary and other conditions, which in general predispose a popu-
lation to contract Cholera, and consequently, which favor the intensity of epidemics are
indigence with all its consequences, the crowding of individuals, their unhealthy
condition, the hot season, deficiency of ventilation, exhalations from a porous soil im-
pregnated with organic matter, above all if that matter be from choleraic dejections.
"As it appears to be shown by experience that the dejections of those with
cholera contain the generating principle of the disease, it is legitimate to admit that
drains, privies, and the contaminated waters of a town, may become agents in the propa-
gation of the disease.
" It seems to result from certain facts, that the ground of a place once impreg-
nated with choleraic matters can for a considerable time retain the power of giving off
the principle of the disease and of keeping up an epidemic, or even of reproducing it
when it has been extinct.
" Question 27th.—What is to be understood of immunity as regards Cholera ?
"Answer.—The immunity which certain localities enjoy, that is to say, the resist-
ance, permanent or temporary, general or partial, opposed by those localities to the develop-