VARIATION OF SALMONELLA PULLORUM 9 



in one type of colony were coccus-like and were not agglutinated by pullorum 

 serum, but gave the same fermentation reactions as the normal type. 



It was observed by White (1928) that rough organisms which were agglutinated 

 in the presence of NaCl (0.85%), were inagglutinable in the presence of the same 

 salt concentration after being extracted with alcohol and chloroform. However, 

 if the rough suspension was heated to 100°C. after treatment with alcohol and 

 chloroform, it was again rendered unstable in saline (0.85%). Smooth strains 

 treated in the same manner remained unchanged. The author concluded that the 

 reaction of denatured rough protein to electrolytes afforded a final test for rough- 

 ness. It was further observed that the most salt-sensitive races were by no means 

 of necessity those which were the most serum-sensitive. It was suggested that the 

 serum-sensitive reaction was due to a special substance or group of substances 

 which appeared to be restricted to certain strains or types. The relation to normal 

 agglutinins was also brought out. The isolation ot a soluble specific substance 

 from the smooth races and not the rough was recorded. He regarded the soluble 

 specific substance as the specific element of the smooth body complex of the 

 Salmonellas . Circumstantial evidence pointed to a relation between soluble 

 specific substance and salt-sensitiveness manifested by certain strains. 



In variation studies with B. subtilis, Soule (1928) found that normal rabbit 

 serum enhanced variation of this organism, while serum homologous to the 

 variant stimulated reversion to the normal type. 



Wilson (1928) reported that daily subculture in broth of Bad. aertrycke, (Mut- 

 ton type), led in about four weeks to a marked change in the composition of the 

 culture, the great majority of the virulent organisms present at the start being 

 replaced by completely avirulent ones. 



Lancefield and Todd (1928) showed that rabbit sera prepared against "Matt" 

 hemolytic streptococci, whether virulent or avirulent for mice, contained type- 

 specific antibody, while sera prepared against completely degraded glossy organ- 

 isms contained no type-specific antibody. 



Two serologically active protein substances and another that was non-protein 

 were isolated by Furth and Landsteiner (1928) from Bad. typhosum. Cross- 

 testing of non-protein substances of various species with the corresponding sera 

 revealed a strong group reaction between Bad. typhosum and Bad. enteritidis. 



Li (1929) reported that "S" forms of the hog cholera bacillus were virulent, 

 while the "R" forms were not. Certain types of variants remained unchanged 

 by serial animal passage. Successful results were obtained in attempting to 

 produce a definite immunity against the virulent "S" forms with the living "R" 

 forms. 



Koser and Styron (1930) demonstrated that smooth forms of Baderium dysen- 

 teriae, Sonne, could be formed from rough forms quite regularly by rapid, succes- 

 sive transfers in dextrose broth incubated at 37°C. In some cases the reversion 

 appeared to be complete, and the rough forms totally disappeared. Rough 

 cultures held on agar slants at room temperature were much more stable than when 

 subjected to daily transfers on the same medium. A tendency toward spontaneous 

 clumping in 0.85 per cent saline solution was observed in the relatively smooth 

 cultures derived from the rough forms. 



In 1930 Plastridge and Rettger reported a most unusual outbreak of pullorum 

 disease. The nature of this outbreak appeared to be an acute septicemia among 

 chicks and mature fowls which manifested marked pathological changes and 

 suffered a heavy mortality. The causative organism isolated from the infected 

 birds presented characteristics which had not been reported for S. pullorum. 

 It failed to grow on nutrient agar containing meat extract, and grew indifferently 



