58 PREPARATION OF CULTURE-MEDIA. 
(f) A solution of litmus may be added just 
_ It f 
rubber = 
glass go cm. ¥ 
Fic. 34.—Siphon, with one-way valve for starting the 
flow of serum. The end of the glass tube is turned over to 
prevent the clot from entering. 
Thermometer. 
Glass and 
Asbestos cover 
7 
Fa SF EF SE SS iF 
fre gauge 
Adjustable legs for 
regulating slant. ia 
= 
Fic. 35.—Coagulator for blood-serum tubes. Providence 
Health Department pattern, with wooden rack for holding 
tubes away from sides. When in use, the four sides and 
the space below are covered with asbestos boards. 
previous to its distribution in tubes, sufficient to 
give the milk a pale-blue color. 
