162 GENERAL MICROBIOLOGY 



Method. 1. Inoculate the medium with the material 

 under investigation and replace the plug. 



2. Cut off the plug even with the mouth of the tube. 



3. Push the plug into the tube, 4 to 5 cm. 



4. Place on top of the plug the pyrogallic acid and only 

 enough of the alkaline solution to saturate the plug. 



5. Insert the rubber stopper and seal with paraffin if 

 necessary. If the cotton is more than saturated, the strong 

 alkaline solution will run through the plug and kill the organ- 

 isms in the culture. 



This preparation is valuable only for noting the presence 

 of anaerobes in any substance or studying the growth of an 

 anaerobe in pure culture, on account of the difficulties of 

 technic. 



2. Giltner's H Tube. This is simply two test tubes 

 connected near their mouths by a short piece of glass tubing. 

 By this method the tube cultivation may be placed in one 

 test tube, the chemicals in the other and both' tubes stop- 

 pered. (Fig. 41, p. 161). 



The use of this apparatus presents a distinct advantage 

 over any other tube cultivation method, as the culture is 

 readily discernible at all times and may be handled without 

 the disagreeable features of the other methods. 



The H tube lends itself also to the method depending 

 upon the absorption of oxygen by an aerobic organism. 



3. Buchner's tube consists of a stout glass test tube 

 having dimensions of about 23 cm. in length and 4 cm. in 

 diameter, fitted with a rubber stopper. i \ 



a. A test-tube culture of the organism or mixed culture 

 to be tested is prepared. 



6. A little cotton, the pyrogallic acid, and sodium 

 hydroxide solution are placed in the Buchner tube, the cul- 

 ture immediately introduced and the rubber stopper imme- 

 diately fitted tightly in the mouth of the large tube. (Fig. 

 42, p. 161). 



4. In Turro's tube, the medium is poured through the 



