70 METHODS OF CULTIVATION OF BACTERIA 



time almost to boiling-point without this occurring. The tissue 

 of the organs gives off something into the medium which favours 

 the growth of anaerobes, as can be shown by placing the tissue 



for some time in the medium 

 and then removing it ; there- 

 after the medium is suitable 

 for anaerobic growth. 



Another convenient method 

 is to use test-tubes, preferably 

 without rims, over the upper 

 end of each of which a piece 

 of rubber tubing about three 

 inches long is fitted ; glucose 

 bouillon is added to the tubes 

 and the rubber tubing is 

 closed with a metal clip. The 

 tubes are then sterilised. For 

 use, the metal clip is removed 

 from a tube, the medium is 

 inoculated, and the tube is 

 gently shaken so as to distri- 

 bute the organisms throughout the medium; the tube being 

 held obliquely, the upper part of the medium is boiled over a 

 Bunsen flame, and then, when steam is still rising, the tubing 

 is closed with the clip. Under these circumstances anaerobes 

 flourish freely. 



When it is desired to grow anaerobes on the surface of a 

 solid medium such as agar, tubes of the form shown in Fig. 26, 

 a and b, may be used. A stroke culture having been made, the 

 air is replaced by hydrogen as just described, and the tubes are 



FIG. 25. Flask arranged for culture of 

 anaerobes which develop gas. 



6 is a trough of mercury into which 

 exit tube dips. 



FIG. 26. Tubes for anaerobic cultures on the surface of solid media. 



fused at the constrictions. Such a method is of great value 

 when it is required to get the bacteria free from admixture of 

 medium, as in the case of staining flagella 



