900 EXPERIMENTAL INFECTION AND IMMUNITY 



(a) Are there symptoms of toxemia in the rabbits? Are these symp- 

 toms alike in both animals? Which is more toxic, the nitrate or the 

 whole culture? 



(b) Does the nitrate enhance the effect of the whole culture? 



(c) If any of the animals succumb, autopsy under aseptic precau- 

 tions. Prepare cultures of the peritoneum and heart's blood on agar 

 slants or in neutral bouillon. Is the typhoid bacillus markedly ag- 

 gressive? 



(d) If there is a peritoneal exudate, prepare smears and stain with 

 carbolfuchsin (1 :10). What type of cell predominates? Are any of 

 the bacilli engulfed in the cells? 



(e) Do any of the bacilli show signs of disintegration? If so, do you 

 know what these changes are due to? 



EXPERIMENT 18. NATURAL AGGRESSINS 



1. Inject a guinea-pig intraperitoneally with 3 c.c. of twenty-four-hour bouillon 

 culture of Bacillus typhosus. 



2. After twenty-four hours, anesthetize the animal and remove the exudate 

 aseptically into 5 c.c. of a 2 per cent, solution of sodium citrate to prevent coagula- 

 tion. 



3. Filter. 



4. Inject three guinea-pigs intraperitoneally as follows: 



1st pig: 3 c.c. of filtrate. 



2d pig: 2 c.c. of twenty-four-hour bouillon culture of 



typhoid bacilli. 

 3d pig: 1 c.c. each of culture and filtrate. 



5. Observe animals for several days, particularly the temperature reaction and 

 weights. 



(a) Is the nitrate alone toxic? 



(b) Does the nitrate appear to enhance the effects of the unfiltered 

 culture? 



(c) If the animals succumb, autopsy aseptically. Make cultures 

 of the peritoneum and heart's blood on agar slants or in bouillon. Pre- 

 pare smears of the exudate and stain with 1 : 10 carbolfuchsin. Do any 

 of the animals show a typhoid bacteremia? Does the filtrate appear to 

 prevent phagocytosis? 



EXERCISE 7. BACTERIAL PROTEIN; PTOMAINS; MECHANICAL ACTION 



OF BACTERIA 



EXPERIMENT 19. BACTERIAL PROTEIN (VAUGHAN) 



1. Inoculate 10 slants of 2 per cent, neutral agar in large bottles with a culture 

 of Bacillus coli and grow at 37 C. for four days. 



2. Add about 10 c.c. of distilled water to each bottle and gently remove the 



