IOWA ACADEMY OF SCIENCES. 
117 
found in the tubes in the incubator from 1 to 2 c. c. of the 
beef tea bouillon is injected intra-abdominally into white 
rats or guinea pigs. Two animals are inoculated. If the 
animals do not die it is regarded as safe. If animals die 
agar cultures are made from the heart’s blood. The plates 
are incubated at the temperature of blood. The colonies 
are carefully studied. The Bacillus venosus seems to be the 
germ which was found in wells suspected to have caused 
the infection of typhoid fever. 
The chemical composition of the medium as has been 
shown by Messrs Winslow, Fuller, Sedgwick and Prescott* 
is important. 
Mr. Winslow especially recommends agar agar, gelatin, 
glycerin agar, and the litmus lactose agar. 
On the importance of the use of this medium Winslow 
and Nibeckerf give the following rather interesting table: 
Sources of Water. 
Average No. of 
Colonies per c. c. 
Gelatin20° 
Wurtz-Agar 37.5° 
Well , spring 
1,664 
28 
Reservoirs 
153 
43 
Ponds 
296 
95 
Taps 
242 
24 
Streams 
273 
101 
In a general average of 259 samples of water studied by 
Winslow and Nibecker they give the following interesting 
summary of their work: 
*Jr. New Eng. Water Wks. Assoc. Vol. 15 : 482. Also Technological Quarterly 16: 
!. 
f Winslow, C. A. E. and Nibsckee, C. P.— Techn. Quar. Vol. 16: No. 3, Sept. 1903. 
