THE VIABILITY OF THE BACILLI’S FESTIS. 
[By M. J. Rosenaii, Passed Assistant Surgeon, Director Hygienic Laboratory, Marine- 
Hospital Service.] 
There are man}" factors that influence the life of the bacillus pestis 
in the outer world. Some of these influences, such as temperature, 
moisture, and light, are well understood. The bacillus withstands dry- 
ing very badly. It can not live long in the direct, warm sunshine. 
High temperatures are iiiA^ariably fatal. 
In the light of these experiments and the published work of others 
we have to modify considerably our views upon the viability of the 
bacillus pestis. It does not always and under all circumstances die in 
so short a time as a few days, as the work of Kitasato and Wilni first 
indicated. We noAv know that the organism may live for months, and 
even years, in a test tube, on a moist albuminous medium. And the 
present work shows that even when dry it may live over four months, 
provided the temperature is cool — less than 20^ C. 
The bacillus of plague can in no sense be considered a tender organ- 
ism, as was at first supposed. It is much easier to cultivate than the 
lanceolate coccus of pneumonia or the pathogenic streptococci. In this 
re.spect it resembles more closely the hardier of the hemorrhagic 
septica^mic group. 
In this laboratorv we have worked with the organism from .seven 
sources: from Djiddah, Oporto, Rio de »faneiro, Bombay, the New 
York Quarantine case, Glasgow, and San Franci.sco, ^^"e find that all 
these seven varieties thrive well on artificial media under the usual 
laboratory conditions. 
We tested the life history of this organism upon a great variety of 
objects and under various conditions. We attempted to imitate natui'e. 
But we can not imitate all the conditions undei’ which the organism 
may exist in nature, and we ought not, therefore, to apply the experi- 
ence of the laboratorv too literally to the life history of the plague 
l)acillus outside of the body. We may determine with fair certainty 
the length of time the bjicillus mav live under given conditions. But 
these conditions are more or less arbitrary, and to a certain extent 
artificial. In general terms, we can state whether it is a hardy organ- 
