EXPERIMENTAL INFECTION AND IMMUNITY 



EXERCISE 5. TOXINS (Continued) PLANT AND ANIMAL TOXINS 

 EXPERIMENT 14. STREPTOTOXIN 



1. Cultivate a strain of virulent streptococci in tubes of slightly alkaline serum 

 or ascites bouillon for forty-eight hours at 37 C. 



2. Inoculate a guinea-pig intraperitoneally with 1 or 2 c.c. of the unfiltered cul- 

 ture. 



3. Autopsy aseptically eighteen or twenty-four hours later. 



(a) What are the gross features of the exudate? 



(b) Prepare smears of the exudate and stain with methylene-blue. 

 Are there many cells present? How do you explain the cellular con- 

 tent? 



(c) Are streptococci present? Are these inclosed by any of the 

 cells? How do you explain the condition? 



,(d) Is the exudate bloody? If so, why? 



(e) Examine your blood-agar plates. Are there any peculiar 

 changes around the colonies? To what are these changes due? Does 

 this have any connection with the bloody character of the exudate? 



(f) Why are streptococcus infections so virulent and spreading in 

 character? 



(g) Is the streptococcus an aggressive microorganism? 

 (h) Do streptococci contain an endotoxin? 



EXPERIMENT 15. PHYTOTOXINS 



1. Secure 0.01 gm. ricin or abrin and dissolve in 10 c.c. normal salt solution or 

 distilled water. 



2. Inject 1 c.c. intravenously into a rabbit. Place the animal in a metabolic 

 cage and collect urine, or catheterize every twelve hours or at death. 



3. Examine the urine for hemoglobin and erythrocytes. 



4. Prepare a 1 per cent, suspension of washed rabbit and guinea-pig corpuscles. 



5. Into a series of six small test-tubes place increasing doses of the ricin or abrin 

 solution as follows: 0.1, 0.2, 0.3, 0.4, 0.5, and 0.8 c.c. Add 1 c.c. of rabbit-cell emul- 

 sion to each and sufficient normal salt solution to make the total volume in each tube 

 equal to 2 c.c. A seventh tube is the corpuscle control and contains 1 c.c. of the ery- 

 throcyte suspension and 1 c.c. of salt solution. 



6. Prepare a similar series of tubes with the guinea-pig erythrocyte suspension. 



7. Shake the tubes gently and incubate for two hours. 



(a) Do any of the tubes show hemolysis or hemagglutination? 



(b) Is the action the same with both bloods? 



(c) Does the plant toxin show a selective affinity? 



(d) Does the rabbit show any evidences of hemolytic jaundice? 

 Are there blood elements in the urine? 



