PHAGOCYTOSIS 905 



(a) Has the serum served to protect any of the mice? 



(b) Is this protection due to bacteriolysins, bacteriotropins, or both? 

 Do antitoxins play any part? 



(c) Why is it preferable to use homologous culture and immune 

 serum? What bearing has this upon the treatment of human pneumo- 

 coccus infections? 



(d) Do you know a method for quickly isolating and identifying 

 pneumococci from sputum? 



Note. This experiment may be conducted with rabbits; also a cul- 

 ture of streptococcus and its immune serum may be used. 



EXERCISE 10. PHAGOCYTOSIS 



EXPERIMENT 30. PHAGOCYTOSIS (MACROPHAGES) 



1. Secure pigeons' blood and defibrinate. Wash the corpuscles several times and 

 prepare a 5 per cent, suspension. 



2. Inject a guinea-pig intraperitoneally with 3 c.c. of this corpuscle suspension. 



3. After three hours withdraw a small amount of peritoneal exudate by means 

 of a capillary pipet. Examine with hanging-drop preparations and prepare smears 

 and stain with Wright's stain. 



4. Make similar preparations twelve, eighteen, twenty-four, and forty-eight 

 hours after injection. 



(a) Has phagocytosis occurred? 



(b) Which cells have become phagocytes? 



(c) Do the pigeon cells appear as if undergoing digestion? 



(d) Which portion of the pigeon cell resists digestion? 



(e) Explain mechanism of intracellular digestion. 



EXPERIMENT 31. PHAGOCYTOSIS (MICROPHAGES) 



1. Place a drop of blood in the hollow cell of a ground-out slide such as is used for 

 hanging-drop preparations. Cover with a clean slide, seal with a ring of vaselin, and 

 place in a large Petri dish containing pieces of filter-paper moistened with water 

 (moist chamber). Place in the incubator for fifteen minutes. 



2. Remove the cover-glass and carefully wash cover-glass and cell with normal 

 salt solution. The erythrocytes are removed and the leukocytes left adherent to the 

 cell and cover-glass. 



3. Fill the cell with fresh serum and add a quantity of culture, preferably a loop- 

 ful of a twenty-four-hour bouillon culture of non-virulent anthrax bacilli. Apply the 

 cover-glass and vaselin the margins to prevent evaporation. 



4. If at all possible, employ a warm stage and watch the process under the micro- 

 scope. 



(a) Does phagocytosis occur? 



(b) Which cells are acting as phagocytes? 



