, 1865-12-15

ed by heat on the one side and cold on the other.
1t prevails, in fact, only in climates having a
range of temperature between 40 deg. and 60
deg. Fahrenheit, At the temperature of boiling
water all these poisons are destroyed-a most
important fact, as we have in every household
in Europe the means of destroying them. But
there are other means of conveyance besides
air and water. Articles of food, articles of
wearing apparel, bedclothes, curtains, carpets,
and all vessels and repositories containing the
secretions of human beings, may retain the
poison cells in all their integrity. These
things may carry the poiSons from household
to household, disseminate them in our streets,
our Omnibuses, our railways, steam ships, and
public cOnveyances of all kinds. The drain
may carry them into the sewer, and the sewer
into the river, but in their course they may
escape from our yentilating shafts, our gully
holes, and open closets. They may be empted
into our wells and rivers, and conveyed to our
bodies by means of spring water or river water.
They may be shut up in drawers or in old clo-
sets (of which there are many striking instances
on recOrd), and any moment when brought in
contact with the human system, they may start
into life and activity again, to renew their raya-
geS On systems predispOsed to their action.
That the poison of disease may exist, and every
possible access to q system be present, and yet
the disease not taken is we'll known. Instances
frequently happen of persons living to an old
age, without having had any of the ordinary
contagious diseases of mankind. 1t would be
we'll to make a more accurate study of these
cases. But we know something of the laws of
predispoSitiOn to disease. We know, for in
stance, that persons who have had the small
pox are not disposed to take it again. We
know that in nine cases out Of ten if persons
have been vaccinated they will not take small
poX. This is one of the great triumphs Of our
modern civilization. 1t is the beacon Of our
hopes with regard to crushing out for ever the
poisOns that can only be prOpagated in human
systems. But our knowledge of predisposition
extends further than this. We know that
where the four great factors of our life have
been scantiIy supplied, or vitiated, there pre-
disposition, not only i'll idiopathic and Self-gene-
rated disease exists, but to receive the germs
of the poison fevers, of which I have been
speaking. So well is this known, thai we can
point out certain external conditions, which
will so act upon the human system ds to pre-
dispose it to certain forms of disease. Thus,
amongst our working men and women. who
live in badly ventilated and OvercrOwded houses,
we find those who are most ready to take the poi
son Of typhus Amongst the underfed, the fever
called relapsing, and which differs from typhus
and typhoid, finds its most ready victims.
Hence it has been called famine fever. But no
class or condition OF men have been discovered
who are not susceptible of these poisons. The
medical man who lives free from the influence
of overcrowding or famine, in his own home, is
frequently stricten down with these fevers.
The anxiety of the student, the statesman, or
the prince, may undermine his health, and rem
der him a ready victim for the poison that lies
concealed like a snake in the grass in his path.
1t is not necessarily among the over-crowded
and badly-ventilated rooms of the poor, and
the squalor and filth Of our lowest classes, that
scarlet fever selects its victims, and commits
the greatest ravages. The homes of the rich,
and the hearths of the comfortable middle class
es of England are made desolate by its all per-
vading scourge, and it is a mockery to say that
we know the conditions of those who will be
the subjects or the victims either of scarlet fe-
yer, or its twin-sister of mischief, diphtheria.
That both these diseases depend on a special
poison, which can be communicated through
the medium of the air, and preserved in activi-
ty on inanimate substances, as clothes and
%excreta, | have no doubt, but we cannot pre-
dict with any certainty who will be their vic
TINS. What is true of human diseases is also
true of those of the lower animals which man
associates with himself. The horse, the OK,
the sheep, and the pig are all liable to idiopa-
THO and contagious diseases. Like human
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