296	PATHOGENIC BACTERIA.
etc.    Whoever comes in contact with such materials is
in danger of infection.
It is of great interest to notice the remarkable results
obtained by Biggs, Park, and Beebe in New York, where
the bacteriological examinations conducted in connection
with diphtheria show that the virulent bacilli may be
found in the throats of convalescents as long as five weeks
after the discharge of the membrane and the commence-
ment of recovery, and that they exist not only in the
throats of the patients themselves, but also in the throats
of their care-takers, who, while not themselves infected,
may be the means of conveying the disease from the
sick-room to the outer world. Even more extraordinary
are the observations of Hewlett and Nolen,1 who found
the bacilli in the throats of patients seven, nine, and in
one case twenty-three weeks after convalescence. The
importance of this observation must be apparent to all
readers, and serves as further evidence why most thor-
ough isolation should be practised in connection with
this dreadful disease.
Park2 found virulent diphtheria bacilli in about i per
cent of the healthy throats examined in New York City.
Diphtheria was, however, prevalent in the city at the
time. Most of the persons in whose throats they existed
had been in direct contact with cases of diphtheria. Very
many of those whose throats contained the virulent bacilli
did not develop diphtheria. He concludes that the mem-
bers of a household in which a case of diphtheria exists
should be regarded as sources of danger, unless cultures
from their throats show the absence of diphtheria bacilli.
In connection with the contagiousness of diphtheria
the recent experiments of Reyes are interesting. He
has demonstrated that in absolutely dried air distributed
diphtheria bacilli die in a few hours. Under ordinary
1	Brit. Med. Jour., Feb. i, 1896.
2	Report on Bacteriological Investigations  and  Diagnosis  of Diphtheria,
from May 4, 1893, to May 4, 1894, Scientific Bulletin No. /, Health Depart-
ment, City of New York.