150 



COLLECTED STUDIES IN IMMUNITY. 



blood for examination of all the animals on the 7th day after the 

 last injection. 



TABLE III. 



It may further be mentioned that examinations were also made 

 on the 29th and 39th day ofter the injection, in which however a 

 decrease of the agglutinating value was usually found. 



Investigations also showed that injections of physiological salt 

 solution in bouillon caused no variation in the normal agglutinating 

 values. 



A further question was whether and to what degree the serum 

 of normal untreated rabbits possesses agglutinating properties on 

 typhoid bacilli. Out of 17 rabbits which were examined for this pur- 

 pose, 10 showed no agglutination in dilutions of 1:20, one serum 

 agglutinated in the dilution 1 : 20, but no higher, 5 others in 1 : 40, 

 but no higher, and only one agglutinated even in a dilution of 1 : 160. 

 (See Table IV.) 



It is therefore a rare exception for normal rabbit serum to still 

 manifest agglutinating powers on typhoid bacilli in a higher dilution 

 than 1:40. It should be remarked that in the above table "0" 

 has always then been put down when the agglutinating value of the 

 serum in a dilution of 1 : 20 = ; for the examinations began with this 

 dilution. 



