180 
TYPHOID FEVEK IN DISTRICT OF COLUMBIA. 
unsterilized tap water at the temperature of wells, 7°-10°, using 100 cc. 
specimens in glass vessels. He could not find it after thirty-one days 
or later. 
Hoffmann (1905) gives interesting results of experiments in aqua- 
rium water. The aquarium contained 30 liters of tap water and was 
inhabited by snails, fish, and water plants. The bacterial count of the 
water before inoculation was 60,000 per cubic centimeter. Enough 
bouillon culture was added to give 300,000 typhoid bacilli per cubic 
centimeter immediately after inoculation. The aquarium was so placed 
as to be exposed to direct sunlight for some hours daily. B. typhosus 
could be recovered after thirty-six days from the water, and after 
two months from the mud. His methods were good. This experi- 
ment is of value in teaching that the action of protozoans in destroy- 
ing t 3 rphoid bacillus is less to be counted on than the experiments of 
Huntemtiller (1905) and Fehrs (1906) would indicate. These inves- 
tigators did not make use of special methods for the isolation of the 
bacillus as Hoffmann did. Hoffmann found many protozoans present 
in the_water of his aquarium, but if they were responsible for the 
disappearance of B. typhosus, their action was much too slow for 
sanitary purposes. Another point of value is the longer viability in 
the mud than in the water itself. Fehrs does not attempt to ascertain 
the absolute longevity of B. t}^phosus, but shows that the addition of 
protozoa to boiled water inoculated with-B. typhosus reduces the 
viability from forty-six to sixty days, to thirteen to nineteen days. 
Jordan, Russell, and Zeit (1904) attempted to simulate the natural 
conditions by suspending permeable sacs containing water inoculated 
with B typhosus in natural bodies of water. These sacs v/ere sup- 
posed to be impermeable to bacteria themselves but to permit the 
exchange of their dialyzable products. The methods of isolation and 
identification employed were of the most modern description. They 
concluded that competing organisms in the water soon outgrew the 
specific bacterium, especially in polluted waters and sewage. In 
Lake Michigan water the bacillus was recovered only up to seven 
days; in Chicago River water, heavily polluted, three days; in the 
drainage canal on the first and second, and in one instance on the 
tenth day; in the Illinois River, three days. Russell and Fuller 
(1906) employing similar methods arrived at corresponding results, 
recovering the bacillus from Lake Mendota water after ten to thirteen 
days, during which the temperature varied between 9° and 23° C. 
In’ sewage, at 21°-29°, the organism lived but three to five days. 
They also made experiments which tended to show that the destruc- 
tion of the organism depends more on the coincident growth of the 
other bacteria than on the influence of dialyzable products. While 
these investigations represent a praiseworthy attempt to copy natural 
conditions, there seems to be some doubt of their success in this 
direction, inasmuch as in the series of Jordan, Russell, and Zeit 
