39 
Xo. 82. — Plagi’e Cultures ox Various Objects Exposed to the Sunlight. 
A two-day-old bouillon culture was reenforced with an oese of an 
agar culture, and then bits of sterilized paper, crash, sponge, and wood 
were saturated with the mixture and exposed in a Petri dish to direct 
sunlight. The temperature in the sun at the time was 33.2° to 3.5.5° C. 
This was on May Id, in Washington. 
Effects of sunlight. 
No. 83. — Spleen of Plague Rabbit Exposed to Sunlight. 
A small piece of the spleen of a rabbit dead of experimental plague 
was exposed in a Petri dish to bright sunlight. May 20.- At the end 
of five hours it was crushed and planted into broth and gave a typical 
growth, which growth inoculated into a mouse killed it in three days. 
The plague organism recovered in pure culture from blood and spleen. 
CONCLUSIONS. 
(1) The bacillus pestis is not a frail organism. It resembles the 
hemorrhagic septicsemic group or the cocco-bacilli as far as its viability 
is concerned. 
(2) Temperature is the most important factor in the viability of the 
plague bacillus. It keeps alive in the cold, under 19° C. , a very long 
time. It dies quickly, especially when dried, at the bod}' temperature, 
37° C. 
(3) Moisture favors the life of the liacillus pestis. It usualh' dies 
in a few days when dry, even in the presence of albuminous matter, 
provided the temperature is above 30° C. It may keep alive and 
virulent when dry for months in the cold, under 19° C. 
(4) Sunlight kills the organism within a few hours, provided the sun 
shines directly upon the organism and the temperature in the sun is 
over 30° C. The efi'ect of sunlight is not very penetrating. 
(5) The virulence of the bacillus pestis is often lost before its 
vegetability. 
(6) It is unlikel}' that new dry merchandise would carry the infec- 
tion. The organism usuallv dies in a few davs on the surface of 
objects such as wood, sawdust, bone, paper, etc. 
(7) Clothing and bedding can harbor the infection for a long tiiiui 
