126 LABORATORY GUIDE IN BACTERIOLOGY 



scissors. Expand these slightly and after closing 

 remove. This forms a small pocket. 



c) Carry i loopful of a 24-hour-old agar culture into 

 this pocket. 



Experiment 2 — 



a) Heat a 24-hour-old broth culture in the water 

 bath for 30 minutes at 60° C. 



b) Inject o. 25 c.c. of this heated culture subcutane- 

 ously into another guinea-pig (or rabbit). 



Observe and compare in both animals the results 

 by taking note of the ante-mortem phenomena and the 

 lesions post-mortem. 



Experiment 3 — 



Prepare two guinea-pigs and inject subcutaneously 

 into one a lethal dose of diphtheria toxin and into the 

 other the same amount of toxin neutralized with a 

 sufficient amount of antitoxin. Compare the results 

 in the two guinea-pigs. 



6. Demonstration of methods employed in munici- 

 pal laboratories for the diagnosis of diphtheria. 



7. Study of B. xerosis. Obtain mucus from the 

 inner angle of the eyelids by stroking with a platinum 

 loop. Make two film preparations, stain one by Gram's 

 method and the other with methylene blue. Make a 

 culture on slant agar and if impure, plate out. Trans- 

 fer cultures to all media from colonies on the plate and 

 study these in the usual manner. 



