78 DIAGNOSIS OF DIPHTHERIA LESSON xvi 



Examination of Diphtheritic Membrane 



(a) Wash the membrane with sterilised saline solution 

 in a sterile watch-glass. 



(b) Snip off a small piece with a sterilised pair of 

 scissors, place it in another watch-glass containing saline 

 solution, and with a sterile glass rod break it up. 



(c) Dip a small platinum loop into the milky suspension 

 and inoculate three serum agar-agar tubes in the following 

 manner : 



Make three parallel streaks on the surface of the 

 first tube ; without recharging the loop make three 

 similar streaks on the surfaces of the second and 

 third tubes. 



(d) Place the tubes in the warm incubator, 

 Examine next morning as follows : 



(1) Place a small drop of sterile water on a clean cover- 

 glass, select a suspicious colony, and with a platinum 

 needle transfer it to the cover-glass. Gently press the latter 

 on to a slide and examine unstained. 



(2) Proceed in the same manner but allow the drop to 

 dry. Pass the film through the flame and stain with 

 gentian- violet (vide p. 57). 



The diphtheria bacilli are easily recognised by their 

 form and grouping, and by the absence of motility. 



