INTESTINAL GROUP 89 



2 hours, or longer if desired. If complete agglutination 

 takes place, the bacteria will have collected in clumps at 

 the bottom, forming a sediment. The supernatant fluid 

 is perfectly clear. By varying amounts of sediment and 

 varying degrees of turbidity of the supernatant fluid, the 

 degree of agglutination may be estimated. A control- 

 tube of a bacterial suspension vi^ithout addition of serum 

 serves as a guide. Controls with normal serum should 

 also be made. 



5. Special study D. — 



a) Make cover-sUp preparations of B. dysenteriae 

 from glucose-agar-cultures 10-12 days old. Involution 

 forms are then plentiful and can be studied. 



b) Also make cover-sUp preparations of B. typhosus 

 from glucose-agar-cultures 10-12 days old. Does it 

 show the same picture ? 



EXERCISE IV. STUDY OF SUBGROUP IV 

 the proteus gkoup 

 References — 



Lehmann and Neumann. 



Jordan, State Board oj Health of Massachusetts, i8go. 



Jordan, Journal of Hygiene, Vol. II. 



Inoculate agar-slants from stock-cultures of Proteus 

 vulgaris, Prot. zenkeri, and Bacillus cloacae. 



1. Routine study. — Observe particularly the action 

 on milk and gelatin. 



2 . Special study A . — Make plates in gelatin and agar, 

 and observe the colonies after 24, 48, and 72 hours. 

 Note the appearance of the colonies of Prot. vulgaris 

 and of Prot. zenkeri on both media. 



3. Special study B. — Inoculate fermentation- tubes in 

 the same manner as for the other intestinal groups. 



