PATHOGENICITY AND TOXIN PRODUCTION 



721 



phospholipin. The protein component aj^pears to be chemically and immuno- 

 logically very similar to the conjugated protein prepared by Morgan and Partridge 

 (1940) from the specific somatic antigen of Sh. shigce. According to Freeman 

 (1943), the somatic antigen of Salm. typhi-murium chemically resembles that of 

 Salni. typhi. 



TABLE 48 

 Reactions of type strains of Salm. typhi to critical test dilutions of type 



BACTERIOPHAGE STRAINS (FROM CrAIGIE AND YeN 1938). 



CL = Confluent Lysis. -f + + = Numerous discrete plaques of subnormal size. 

 T- = Few plaques, subnormal in size except in Type C strains. 



Pathogenicity and Toxin Production. — As has already been pointed out (p. 703), 

 members of the Salmonella group are widely distributed in the animal kingdom. 

 Broadly speaking, the type of disease with which these organisms are associated 

 is either an enteritis or a septicaemia. In man, a few species, like Salm. typhi 

 and Salm. paratyphi B, give rise to a disease characterized by a fairly long incuba- 

 tion period and the predominance of septicsemic over intestinal symptoms. The 

 great majority, however, of the Salmonella species produce acute gastro-enteritis 

 of the food-poisoning type in children and adults, or acute enteritis in infants 

 characterized by a short incubation period and the predominance of intestinal, 

 over septicaemic symptoms. Nevertheless, a disease apparently starting as an 

 enteritis, may become a septicaemia, which runs a typhoid-like course or is associated 

 with localized manifestations of disease in the meninges, bones, joints, or other 



