106 INTRODUCTION TO IMMUNOCHEMICAL SPECIFICITY 



the same phase for a number of generations, but is always capable 

 of giving rise to the other phase. As a matter of fact, the antigens of 

 either phase may occur in various types, although the specific antigens 

 are generally restricted to a smaller number of types (Dubos, 1945). 

 These complicated antigenic properties of the Salmonella can be a 

 source of confusion unless they are understood. 



TABLE 8-2 

 Somatic and Flagellar Antigens in Certain Common Salmonella* 



* Modified from a table in Bacterial and Mycotic Infections of Man, edited by 

 R. J. Dubos, 1952. Courtesy of Dr. Dubos, Dr. H. R. Morgan, J. B. Lippincott 

 Co., and the National Foundation for Infantile Paralysis. 



•^ Parentheses indicate that the antigen is not invariably present. 



It was formerly the practice to designate the somatic (O) antigens 

 by Roman numerals, as shown in Table 8-2, but following a decision 

 made in 1953 at the Sixth International Congress of Bacteriology in 

 Rome, the workers who have recently contributed so much to our 

 knowledge of the chemical structure of these antigens, employ 

 Arabic numerals. I shall follow this usage. It was former practice 

 to denote the species flagellar antigens by small Roman letters, and 

 the group flagellar antigens by Arabic numerals. Thus Salmonella 

 nczvport possesses O antigens VI and VIII, species H antigens e and 



