664 



STABILITY OF BACTERIAL SUSPENSIONS. Ill 



agglutinin forms a film on the surface of the organism. As soon as 

 the layer is complete the addition of excess serum will have no effect. 

 If this assumption is correct, it follows from Table V that agglutina- 



125 



100 



c 



o 



CO 



£ 100 



o 



O 



75 



0.00016 O.0008 0.004 0.02 

 Concentration of serum 



50 



25 



0.5 1.0 2.0 4.0 8.0 



Concentration n NaCl 



Fig. 6. Upper half, effect of the concentration of immune serum on the co- 

 hesive force between two films of B. typhosus in 0.10 N NaCl. Lower half, effect 

 of concentration of NaCl on the cohesive force between, a, smears treated with 

 immune serum and, b, untreated smears. 



tion occurs when the surface is about one-eighth covered. The 

 inhibiting effect of strong salt solution is, as usual, due to the decrease 

 in the cohesive force, when the organisms are not completely covered 

 with immune body. 



