96 CULTIVATION OF ANAEROBIC MICRO-ORGANISMS 



2. When it has cooled, sow the medium through a ; then with a pipette fill the 

 bulb B one- third full of potassium pyrogallate. 



3. Replace the stopper C and lute it with paraffin or Golaz's wax. Tilt and 

 rotate the apparatus so that the pyrogallate runs all over the surface of the bulb 

 to accelerate the absorption of oxygen. Incubate. 



[H. Bulloch's method. Method recommended. Bulloch's method is a 

 modification of the preceding, designed to allow of the incubation of a number 



of plates or tubes at one time. The principle is the same and depends upon 

 the absorption of oxygen by pyrogallate of potassium. The apparatus con- 

 sists of a circular glass bell jar (fig. 87) flanged below, with two openings 

 above, each of which is fitted with a ground-glass stopper prolonged into a 



Y/////A 



FIG. 88. A modified form of Bulloch's apparatus. 



glass tube bent at right angles and fitted with a closely fitting tap. One of 

 these tubes only passes a few centimetres into the bell jar while the other 

 reaches nearly to the bottom. 



[Fig. 88 shows a slightly modified and less fragile form of Bulloch's 



