" An infection is the morbid process induced by the invasion and
growth in the body of pathogenic micro-organisms."

This definition, which seems to be quite clear and concise, is laid
down by Osier in a recent edition of his work on the Practice of
Medicine. From it we infer that all the so-called contagious diseases
are infectious, and I believe that to be the more correct and modern
view ; if we discard the word contagious altogether, and hold to the
use of the word infectious, our understanding of this class of diseases
will be much facilitated and our knowledge rendered much more
accurate. As an argument in favor of this view, we find that con-
tagion is a noun without a verb formation, whereas the word infec-
tion is derived from the Latin verb inficio, and has its verb, noun,
adjective and adverb, of easy formation in the English ; furthermore,
the real difference in the meaning of these words is so slight that to
use both serves to confuse rather than to enlighten. According to the
definition one might infer that, if pathogenic micro-organisms enter
the body, infection is sure to follow ; that such is not the fact, we
have abundant proof. We know that to a very large degree vaccina-
tion produces immunity from smallpox and age from the infectious
diseases of children. A case of scarlet fever may break out in a
school room of forty pupils, and but one or two additional children
be affected by the exposure ; it is not reasonable to suppose that but
one or two pupils breathed the germs, or the poison of this disease,
into their throats and lungs. To me it is not reasonable to suppose
that but one or two pupils really took the poison into their systems;
it has been demonstrated, beyond a doubt, that diphtheria germs
have been present, for days in the throats of nurses, attendants and
others, without producing a single symptom characteristic of this
malady ; is it not reasonable to suppose that, having gained entrance



198 MEDICAL SOCIETY OF NEW JERSEY.
