41 STUDY OF PATHOGENIC BACTERIA 



I. Pyo genie cocci. 



Staphylococcus pyogenes albus. 

 Staphylococcus pyogenes aureus. 

 Staphylococcus pyogenes citreus. 



to contrast with 

 Micrococcus candicans. 

 Micrococcus agilis. 



i. Prepare subcultivations from each: 

 Bouillon, 



Agar streak, 



.Jf , and incubate at 37 C. 



Blood serum, 



Litmus milk. 

 Agar streak, 

 Gelatine stab, 

 Potato. 



and incubate at 20 C. 



Compare the naked-eye appearances of the cultures 

 from day to day. Note M. agilis refuses to grow at 

 37C. 



2 . Make hanging-drop preparations from the bouillon 

 and agar cultivations after twenty-four hours' incu- 

 bation. Examine microscopically and compare. Note 

 the locomotive activity of M. agilis and the Brownian 

 movement of the remaining micrococci. 



3. Prepare cover-slip films from the agar cultures, 

 after twenty-four hours' incubation. Stain for flagella 

 by the modified Pit field's method. Note M. agilis is 

 the only micrococcus showing flagella. 



4. Make microscopical preparations of each from all 

 the various media after twenty-four and forty-eight 

 hours and three days' incubation. Stain carbolic 

 methylene-blue, carbolic fuchsin, and Gram's method. 

 Examine the films microscopically and compare. 

 Note in the Gram preparation, the Gram negative 

 character of certain individual cocci in each film pre- 

 pared from the three days' growth such cocci are dead. 



5. Stain section of kidney tissue provided (showing 



