VARIATION OF SALMONELLA PULLORUM 15 



According to the results tabulated in Table 2, it is apparent that certain factors 

 are operating which are difficult to explain. The character of the agglutination 

 or settling differed among certain antigens. Some antigens appeared unstable 

 in 0.9 per cent saline solution, but in the presence of negative serum the cells 

 remained in suspension. In one instance (antigen 5) agglutination occurred in a 

 dilution of 1:640, but not in 1:1280. In the latter dilution the cells remained in 

 suspension, but settled out in the antigen control. With antigen 6, it also appears 

 as if the serum had a stabilizing effect in maintaining the cells in suspension. 

 On the other hand, in some cases the serum definitely appears to have an opposite 

 effect. Furthermore, antigens may vary to such an extent in their mosaic that 

 they may react differently when placed under certain uniform conditions. 



Table 2. — Reactions of variants with positive and negative pullorum sera. 



Strain Agglutination Titre Antigen 



No. Sera Control Remarks 



10 20 40 80 160 320 640 1280 



1 /?_ i ? _i ? _i ? _4 ? _ i ? _ 4? PS PS Muddy type of agglutination 



2 



3 



4 



5 



\N SS SS SS SS SS SS 



Fluffy precipitate in first ."> tubes 



Muddy type of agglutination 



Antigen appeared clumpy 



9 /P 4? 4? 4? 3? 1? 0-0 Cells suspended in .22% saline solution 



10 



11 /P 4? 4? 4? 4? 3? 2? 2? 2? Cells suspended in .22% saline solution 



\N SS SS SS 



13 /P 3? 3? 3? 2? 2? SS SS SS Cells suspended in .22% saline solution 



\N 



Legend: P — positive serum 

 N — negative serum 



4 — complete agglutination 



3 - incomplete agglutination 



2 — partial agglutination 



1 — slight agglutination 



— no agglutination 



? — questionable agglutination 

 CS ■ — ■ complete settling of cells 

 PS — partial settling of cells 

 SS — slight settling of cells 



Because of the influence of salt concentration upon the ability of a strain to 

 remain in suspension, the twelve strains were suspended in different salt concentra- 

 tions (0.11, 0.45 and 0.90 per cent) and tested against positive and negative 

 pullorum sera. The method of preparing the antigens and the technique for con- 

 ducting the agglutination test were the same as employed previously. 



The data presented in Table 3 confirm the observations recorded in Table 2 

 in many respects, and show beyond a doubt that a decrease in electrolyte will 

 increase the stability of the organism when in suspension. In no case was settling 



