Book I CONTAGION 57

those which in our time have appeared in Italy and are called
by some 'lenticulae', by others 'puncticulae!.38

I will mention also an unusual contagion which, in the year
1514, attacked cattle only, first observed in the district of Friuli;
then gradually it was carried to the Euganeans, and thence to
my own countryside.3? At first the cattle abstained from food,
for no manifest reason. But when the herdsmen looked into
their mouths they saw a sort of roughness and small pustules
on the palate and the whole mouth, and the infected animal
had to be removed at once from the herd, or the whole herd
became infected. Gradually this distemper descended to the
shoulders and thence to the feet, and in cases where this change
took place almost all the animals were cured, but when it did
not, they nearly always died.

Now of these contagions which come from without, the air^?
is the most potent cause, though they may also come from.
water, marshes and other sources. 'The air is the most suit—
able medium, partly because it very easily receives both its own
and foreign infections, and because we have to use it to live.
And we must not fail to observe that the air is sometimes mere—
ly modified by becoming heated, or cooled, or drenched, or
dried, but sometimes it not only alters thus, but also transmits
to our bodies foreign vapors, which are themselves not 'simple,'
but are also germs of contagions. Now the difference between
& simple vapor and the germ of a contagion is that a vapor is
a highly alterable thing made of a combination which is not
strong and viscous, such as that of which the germ is made.
Nevertheless, vapors that have been imported into our bodies
concur in manifold ways to produce the putrefactions that arise
therein. In the first place, they cause obstruction (of the
humors), secondly they provide a locus for foreign heat and
moisture, finally, when mingled with the humors, they make
these hostile and unfriendly to the organs, from which they are
rejected and abandoned by nature, and thus they putrefy.
Germs however, not only do all this, but do it in the highest
degree, and at the same time procreate other germs precisely
similar to themselves, as progeny, which, when carried to an—
other object, transmit the contagion to it.

Accordingly, when the air carries into our bodies merely the
simple vapors, that is not, so far, contagion, nor is the malady
contagious per se, provided that there does not result a deep—