388 



IMMUNOLOGY 



macroscopic Widal and the second is Huddleson's rapid spot 

 plate method. Descriptions of these respective techniques are 

 given by Kolmer and Boerner (1941) p. 596 or Gradwolil (1938) p. 

 923. 



Tularemia. — Tularemia is a disease primarily of rodents and 

 secondarily of man. Some valuable immunological studies can be 

 made with this organism. It offers an interesting opportunity to 

 study the agglutinin titer in uninfected tame rabbits which have 

 never been exposed to infection as well as the titer in the normal, 



8 lb 



Days after Tr.f«et. 

 RaV>b.t: 2»2 



Pig. 17. — Graph showing- fluctuation in asglutinins in partially immune and im- 

 mune animals during- infection -with P. tularensis. (After Downs.) 



partially immune and immune rabbits following and during infec- 

 tion. Downs ( 1932 ) has extensively investigated these phenomena. 

 Agglutinin Response to Infection in Partially Immune 

 Animals. — Fig. 17 shows the fluctuations in agglutinin titer in a 

 partially immune rabbit, Number 282, and a highly immune rabbit, 

 Number 274, following the intradermal injection of a dose of living 

 organisms that would kill a normal i-abbit within a few days. It is 

 interesting to note the drop of agglutinin titer simultaneously with 

 the appearance of the bacteria in the blood stream. 



