pigment was produced from these colonies. From a third tube of the 

 series, in addition to the giant colonies came colonies mth highly- 

 convex centers each surrounded by an annulus of thin, flat, transparent 

 growth with entire edge. Platings from a fourth tube yielded again the 

 colony types described for tube 3, and in addition numerous colonies, 

 approximately 1.5 ram. in diameter, with a roughened surface. Examination 

 with a hand lens showed that the roughness was due to the presence of 

 large numbers of secondary papillae on and below the surface of each 

 colony. 



There vrere thus three abnormal colony types arising out of the 

 passage of the organism through phenol broth — giant, annular, and 

 papillated colonies. Further platings on nutrient agar were made from 

 the giant colonies, from the central body and annulus of the annulated 

 colonies, and from the papillae of the papillated colonies. Saline 

 suspensions of the giant colony samples spread on nutrient agar plates 

 shared an immediate reversion to the normal stock-colony type. Similar 

 results were obtained i.vith transplants of the annulated colonies. 



In contrast to the complete reversion of these variants, platings 

 from papillae showed colonies of the original type (stock culture type), 

 and in addition about equal numbers of a new colony form, together irith a 

 number of colonies of an intermediate type. Selected colonies of the two 

 distinct types when replated gave rise only to colonies of the same 

 description as that of the parent colony, whereas platings from the 

 intermediate type of colony always shovred a further breaking up into two 

 major and the intermediate colony types. These two major colony types 

 ware quite distinct. One was opaque, strongly convex, and cream-colored. 

 The other was translucent, only slightly convex, and showed a slight but 

 definite bluish-green color by transmitted light. The cream-opaque 

 type proved nonpathogenic, the green- translucent, pathogenic. 



Summaiy of B. salmonicida Dissociation in Phenol Broth Series 



From Phenol Broth came — 



(1) Giant colora.es . These colonies arose on nutrient agar 



(2) Annulated colonies. after up to four subcultures in 



(3) Papillated colonies. phenol broth. 



Giant and annulated colony types when spread on nutrient agar 

 plates showed immediate reversion to the normal stock-colony type. 



Platings from, the papillae of the papillated-colony type showed 

 colonies of the stock type, plus a new colony form and colonies of an 

 intermediate tj'pe. 



Selected colonies of the two distinct types when replated gave 

 rise only to colonies of the same description as that of the parent 

 cclonj'^. 



22 



