METHODS OF INOCULATION 



Growth will take place in both tubes, but the tube 

 exposed to light will show less pigment than the 

 tube kept in the dark. 1 



(4) The Bacillus prodigiosus requires oxygen for its 

 pigment production. 



(a) Draw out a fine capillary pipette and fill its bulb with 

 a small quantity of a fresh broth culture of the Bacillus 

 prodigiosus (eighteen hours old). This is best done in 

 the following manner. 



(b) Fuse both ends of the freshly made pipette, which is 

 naturally sterile, and thrust it through the loosened cotton- 

 wool plug into the culture fluid, breaking its point by 

 pushing it against the bottom of the tube. 



(c) As the bulb of the pipette cools the liquid is 

 gradually sucked up. When the pipette is full, withdraw 

 it and again fuse the broken end. 



(d) Now sterilise the other end by passing it several 

 times quickly through the flame and push it through the 

 loosened cotton-wool plug into a stab gelatine tube. 



(e) When it has cooled down sufficiently, thrust it 

 through the gelatine against the bottom of the tube in 

 order to break the end of the pipette. 



(/) Then withdraw it into the centre of the gelatine 

 and apply gentle warmth to the bulb, until a minute drop 

 of the liquid exudes. 



(g) Now allow the bulb to cool again, and when the 

 liquid has run back, withdraw the pipette. In this manner, 



1 This is contrary to the experience of some observers, who state 

 that the intensity of pigmentation varies directly with the amount of 

 light supplied. 



