BY R. GREIG-SMITH. 



77 



On the teuth day other tests were plated. 



A2 (phosphate), typical colonies of Al as well as transition colonies 



ol' the same. 

 A2a (citrate), typical colonies of Al. 

 B2 (cale. sulph.), colonies of Bl with 2 % of B2. 

 B2 (phosphate), colonies of Bl. 

 B2 (citrate), colonies of Bl. 

 The disappearance of the ropiness in the test with magTiesium sulphate iirst 

 suggested the possibility of there being a phase of B2 secreting a digestive sub- 

 stance akin to Al, and the actual presence of this phase Bl upon the plates led 

 to the examination of the stock culture. The latter was found to be pure B2 and 

 the conclusion was reached that bacterium A was not peculiar in alone possessing 

 phases or conditions with less physiological stability than races. 



Part of expei-iment xvii. was repeated to confirm the changeability of phase 

 B2, in media containing 1 % of dextrose, 0.25 % of meat-extract, and 0.1 % of 

 anhydrous magnesium sulphate, sodium chloride or sodium lactate. 



Plates were prepared- on the eighth day. 



A2 (magn. sulph.), Al, coarsely granular as well as transition fonns. 



A2 (sod. chloride), Al with stippled centre. 



B2 (mag-n. sulph.), Bl, some with stippled centres. 



B2 (sod. chloride), phase Bl. 



The experiment confirms the previous one, and shows the alteration of phases 

 A2 and B2 into phases Al and Bl, in the presence of dextrose, some aid being 

 possibly given by the salt. 



Typical colonies of phase B2 wei'e ])ut into l)ottles containing dextrose with 

 mixed salts and into s-lycerin with sodium phosphate, both with meat extract as 

 a nitrosi'enous nutrient. No ropiness had occurred by the third day when plates 

 were prepared . The glycerin contained phase Bl and B2 with transition colonies . 

 The dextrose did not alter phase B2. 



Tyijical colonies of phase B2 were seeded into fluid media containing 3 % of 

 levulose or dextrose with 0.2 % of potassium citrate and 0.25 % of meat- 

 extract. In four days the dextrose medium was ropy, while the levulose was 

 not, and both contained the introduced phase in pure culture. By the seventh day 

 the ropiness had disappeared in the dextrose flask, but plate cultivation showed 

 that it contained the introduced cohesive phase B2 only. The levulose meHum 

 contained the cohesive and introduced phase B2, together with 25 % of the diffuse 

 pha.se Bl. The diffuse phase is akin to Al, but differs in being brownish or pale 

 buff instead of yellowish or pale straw. Furthermore, there is the suggestion of 



