FURTHER STUDIES ON THE DYSENTERY BACILLUS. 319 



From the large number of experiments which I have made with 

 dysentery and typhoid bacilli I have selected only those which may 

 serve to demonstrate my point. Using the dysentery immune serum 

 described above I found it easy to demonstrate the Eisenberg-Volk 

 phenomenon both with my original dysentery culture and with a 

 Kruse culture. The method was as follows: An agar culture w r as 

 suspended in 10 cc. of an 0.85% salt solution. At first this was used 

 in the living state; later on, after it had been found that there is no 

 difference in the action of living and dead culture, the culture was 

 used with the addition of 0.02 c.c formalin (40%). One cubic centi- 

 meter of this suspension was put into each tube, and decreasing 

 amounts of the immune serum ( 2 /io, 2 /2o, 2 /4o> etc., usually up to 

 2 /5i2o) added, the total volume in each of the tubes being 2 cc. The 

 tubes were then kept in the thermostat at 37 C. and inspected at 

 the end of 2, 5, and 24 hours, both with the naked eye and with a 

 magnify ing-glass. The results were noted as follows: 



no agglutination; 

 trace agglutination; 

 + microscopically distinct but feeble; 

 + + very distinct; 

 + + + entirely clear fluid with an agglutinated sediment. 



TABLE IV. 



The objection was made that the agglutination was hindered 

 in the low dilutions by the large amount of serum present in the 

 tubes. This was met by a corresponding addition of normal serum, 

 and of other fluids (gelatine, mucilage, etc.) to the other dilutions. 

 In the old dysentery serum the question as to the development of the 



