Book I —— CONTAGION 51

pityocampe,3* and cantharides, which are called 'putrefac—
tive'. However they do not cause putrefaction, they burn;
and what evaporates from them cannot be a germ of contagion,
because it is dry. Therefore poisons that are hot and burn—
ing are for that very reason not contagious. But those also
that are cold and stupefying do not cause putrefaction, hence
they too do not convey contagion. It is thus that contagions
differ from. poisons.