DIPHTHERIA. 49 



cork and wire of the swab tube are now withdrawn and 

 the cotton-wool plug is inserted into the culture tube 

 and passed onwards until it reaches the sloped surface 

 of the medium. It is then rubbed gently on the latter 

 and twisted round and round so that every part of the 

 swab may come into contact with the medium. If there 

 is a piece of membrane special care should be taken to 

 see that it is rubbed on the surface, for it is here that 

 we are most likely to find the bacilli. The swab is now 

 withdrawn and replaced in the tube, and the cotton- 

 wool plug of the culture tube singed and replaced. 



The tube thus inoculated must now be incubated for 

 about 18 hours at a temperature not exceeding 37 C., 

 and is then ready for examination. 



Hewlett has suggested a useful method which may 

 be carried out without any special apparatus, the white 

 of a hard-boiled egg being used as the culture medium. 

 Take a fresh egg and boil it for ten minutes or more 

 and allow it to cool. Now take a narrow-mouthed 

 wineglass (or a wide-mouthed bottle, which is better) 

 and rinse it out with perchloride of mercury lotion. 

 Sterilise a knife by passing it slowly through the flame, 

 and cut off the top of the egg, care being taken not to 

 cut into the yolk. Invert the egg into the wineglass 

 (which must be narrow enough to prevent the egg from 

 dropping down into it) taking care that none of the 

 lotion touches the cut surface. This is the culture 

 medium, and it is sterilised ready for inoculation. At 

 a pinch it may be incubated in a warm corner near the 

 fire, near the hot water cistern, or other warm place. 



