Some Biochemical Differences 429 



in media containing 2.5% NaCl, though it has a lag of seven to 

 ten days. It is morphologically normal when so grown. 



TABLE 1 



Adaptation of Cl. Nigrificans to a Saline Environment 

 Stain 74T was Subcultured under N; at 50C. in Baars' (1930) Medium 

 Containing Thioglycollate (c 10 -^M) and Extra NaCl as Indicated Below. 

 Growth was Visible in 24 hours. 



Period Before 

 NaCl Concentrations (%) Growth Visible 



Number of Subculture Highest Tolerated Next Highest (Days) 



1 1.25 2.5 2 



2 2* 2.5 7 



3 2 2.5 10 



4 2.5 2 



* This culture failed to grow again, and one with 1.5% NaCl was used as 

 parent for the third subcultures. 



PRESENT WORK 



For the work reported in this paper two strains of D. desiil- 

 furicans were used, the fresh-water Hildenborough strain (NCIB 

 8303) and the salt water stain El Agheila z (NCIB 8380). These 

 were the same strains as were studied by Littlewood & Postgate 

 (11) who mentioned their origin; El Agheila Z was of the "inter- 

 mediate halophilic iy^e" illustrated in Figure 1. Two additional 

 strains feature in the third section of the work reported here 

 and are mentioned there (11). The strains were maintained 

 as described by Littlewood & Postgate in lactate-yeast extract 

 —sulphate media ("Tryptone," mentioned by those authors, was 

 not included); media were supplemented with 2.5% NaCl for the 

 salt water types. 



For certain purposes a sub-strain of the fresh-water strain 

 Hildenborough adapted to growth with 2.5% NaCl was obtained. 

 Though the strain grew on first subculture in such a medium, 

 growth was restricted to the walls of the tube and the organisms 

 were morphologically most unusual, appearing as straight or 

 broken-looking rods two to three times the length of the original 

 vibrio; the mean length of 1.6," (range 0.9 to 2.5) increased to 

 3.75,u (range 2.1 to 7/'). By the fourth passage, growth through- 



