132 



BACTERIOLOGY. 



In the method recommended by Frankel a tube of gelatine is 

 liquefied, and inoculated. A gutta-percha stopper is substituted 

 for the cotton-wool plug (Fig. 66). It is perforated by two holes, 

 through which two tubes pass which are bent at a right angle. 

 One tube only just passes through the stopper, the other reaches 

 down to the bottom of the test-tube. The 

 horizontal part of each tube has a narrow 

 neck. . The long tiibe has a plug of steril- 

 ised cotton-wool, and is connected with 

 a short piece of india-rubber tubing by 

 which it can be connected with Kipp's 

 apparatus. The hydrogen drives the air 

 out of the liquefied jelly and out of the 

 test-tube, and after about half an hour 

 the horizontal tubes are sealed up, and 

 the test-tube is made into a roll culture. 



Liborius employs a tube with a narrow 

 neck and a lateral arm (Fig. 67). The 

 tube is filled up to the height of the arm 

 with either nutrient agar or a mixture of 

 nutrient agar with 2 per cent, of grape- 

 sugar. The liquefied jelly is inoculated 

 in the usual way, and hydrogen passed 



I through the lateral arm. When the air 



ll ' has been completely driven out, the tube 

 ^ iiiliilll is sealed up. 



To cultivate anaerobic organisms in 

 broth, such as the tetanus bacillus, a fiask 

 is inoculated with the bacillus, and a 

 stream of hydrogen is passed through the 

 broth by means of a tube passing down to the bottom of the 

 flask. The air in the flask escapes by a lateral arm which is bent 

 down at a right angle, and immersed in a capsule of mercury. 

 When the air has been completely expelled the entrance tube is 

 hermetically sealed, and the mercury in the capsule prevents any 

 air from re-entering the flask by the lateral arm (Fig. 68). 



J 



Tig. 67. — Anabeobic Cul- 



TURB-TDBB (LlBOBIUS). 



Method op Fixing Cultures. 



The colonies in plate-cultivations and the growths of bacteria 

 in test-tubes may be stopped at any stage of their growth, and 

 permanently fixed by exposing the culture to the fumes of formic 



