830 EXPERIMENTAL INFECTION AND IMMUNITY 



(c) Can you make out the phase of fixation and phase of ingestion? 



(d) By what agencies do leukocytes kill engulfed bacteria? 



EXPERIMENT 32. PHAGOCYTOSIS 



1. Inject a guinea-pig intraperitoneally with 5 c.c. of finely divided cinnabar 

 suspension and 1 c.c. subcutaneously on each side in the region of the inguinal lymph- 

 glands. 



2. Autopsy the animal at the end of twenty-four hours. Prepare hanging-drop 

 preparations and smears of the peritoneal exudate (stained lightly with methylene- 

 blue). Prepare sections of the inguinal and abdominal lymphatic glands. 



(a) Has phagocytosis occurred in the peritoneal cavity? Which 

 cells have become phagocytic? 



(b) Do you find phagocytes in the lymph-glands? Where are the 

 leukocytes situated? Which cells have become phagocytes? 



(c) How did the material reach the glands? 



(d) How do you explain the presence of cinnabar in the endothelial 

 cells of the gland? 



EXERCISE U. CHEMOTAXIS 

 EXPERIMENT 33. POSITIVE CHEMOTAXIS 



1. Inject a guinea-pig intraperitoneally with 1 or 2 c.c. of a twenty-four-hour 

 culture of Staphylococcus aureus. 



2. Autopsy the animal eighteen hours later and prepare smears of the exudate, 

 Fix with methyl alcohol for five minutes, dry, and stain with carbol-thionin, Wright's 

 or Loeffler's methylene-blue, counterstained with eosin. 



3. Prepare cultures of the peritoneal exudate. 



(a) Describe the exudate. 



(b) Has phagocytosis occurred? 



(c) Which cells are actively phagocytic? 



(d) Are all the cocci engulfed? 



(e) Are there any evidences of the cocci undergoing intracellular 

 digestion? 



(f) Could a sterile substance call forth an exudation of leukocytes 

 when injected into a serous cavity? 



EXPERIMENT 34. NEGATIVE CHEMOTAXIS 



1. Inject a guinea-pig intraperitoneally with 0.5 to 1 c.c. of a forty-eight-hour 

 serum bouillon culture of virulent streptococci. 



2. Autopsy at the end of eighteen to twenty-four hours if death has not already 

 occurred. 



3. Prepare cultures in serum bouillon and a number of smears. Stain the latter 

 with methylene-blue or according to Gram. 



