(1909) noted scanty growth with involution forms on agar, her results 

 of that year have not been generally upheld. She also claimed that 

 pigment production on agar occurred later and was much less pronounced 

 than on other media (Plehn 1911). 



Williamson (1928) found a delicate growth of small transparent 

 colon-ies on agar plate in 24- hours at 15° to 20° C, In 7 days colonies 

 were on the average 1 ram, in diameter, circular, raised, slightly 

 brownish in color, serni-opaque, moist and glistening. Later pigment 

 diffused into the mediimi which becam.e dark brown. Growth similar to 

 that on agar plate occurred on agar slant. 



Duff and Stewart (1933) found that B. salmonicida grew well on 

 peptone meat-extract agar with fairly wide range of pH (6.0 to 8oO) for 

 good grovrth. A whitish, effuse, glistening, convex, translucent grovrbh 

 appeared in 2 days. Growth later became abundant and brownish gray, 

 the medium becoming brovm. In 3 to 6 days pigment becomes coffee brown 

 (Arkwright 1912, Duff and Stewart 1933). 



On serum agar Williamson (1928) found growth exceptionally 

 abundant with intense pigment production. 



Fairly good grovvth occurs on 0,5 percent bile-salt agar according 

 to Artovright (1912). 



On blood agar hemolysis rapidly occurs (Williamson, 1928). Duff 

 and Stewart (1933) noted hemolysis in 2 to 3 days en rabbit blood 

 agar plates, the colonies becoming greenish about the seventh day. 

 Stevens and Keil (1931) isolated a strain of B. salmonicida which 

 showed no hemolysis after L4 days but such a finding is exceptional. 



Broth 



A fine flocculent growth appears throughout the medium with a 

 sediment upon the sides and bottom of the tube (Williamson 1928, Duff 

 and Stewart 1933). A marked growth is visible after 18 to 2^ hours 

 (Marsh 1903, Stevens and Keil 1931). Marsh (1903) claimed that a 

 delicate pellicle might form after 5 days. The appearance of pigment 

 in broth is variable. Stevens and Keil (1931) found it after the third 

 dayj Williamson (1923) stated that she observed it only after 2 months; 

 and Mettara (191^) records that very little pigment is produced in broth. 

 According to Duff and Stewart (1933) a brown ring of pigment forms at 

 the top of a broth tube in 10 to 20 days, which gradually diffuses 

 throughout the m.edium. 



Arkwright (1912) found that in fish broth growth was vigorous 

 but that pigment production was poor in peptone beef broth. 



11 



