164 



BACTERIOLOGY. 



In this laboratory the Koch sterilizer has been entirely sup- 

 planted by the simple sterilizer 1 shown in Fig-. 26. It may be consid- 

 red as a modification of the former. It consists of the ordinary 

 Hoffmann iron water-bath, which has an internal diameter of 18 cm., 

 and a copper pail (20 X 20 cm.) which is provided with a perforated 

 bottom. Two perforated rings, on the inside, allow the passage of 

 steam, and prevent the cotton of the tubes from resting ag-ainst the 

 side of the pail. 



FIG. 26. The author's steam sterilizer, a An ordinary Hofmann's iron water-bath, 

 18 cm. in diameter; b Copper sterilizer; c Support blocks. 



The copper pail is filled with the gelatin tubes, and 

 is placed on the water-bath, in which the water should be 

 actively boiling. In from five to seven minutes steam will 

 issue rapidly, from the tube in the cover, showing that the 

 temperature in the interior has reached 100. The steam- 

 ing" is then continued for an additional 15 minutes. This 

 process is now repeated, on each of the following two days. 

 By means of this simple sterilizer, the student is enabled to 

 perform all the necessary sterilization at his own table. 

 Practically no time is lost in waiting for the generation of 



1 Centralblatt fur Bakteriologie, Bd. 22, p. 340, 1897. 



