502 



G. H. DREW. 



attempts are made to make plate cultures on board a small boat 

 in rough weather, a very delicately swung table will be necessary, or 

 else the roll-tube culture method must be employed. 



Three plates on Peptone Agar were made from each sample, 1 c.c. of 

 the sample being used for each plate. The plates were kept at the 

 room temperature, averaging about 20' C, and the colonies were well 

 developed after 48 hours : they appeared to be all of one kind. A 

 count gave the following results : — 



Depth ill fathoms. 



... 



10 ... 



20 ... 



30 ... 



50 ... 



70 ... 



80 ... 



Number of colonies developing 

 from 1 CO. of sample. 



9 

 6 

 5 

 6 

 30 

 20 



The increase in the number of colonies at 70 and 80 fathoms is some- 

 what remarkable, but no conclusions in this respect can be drawn from 

 one series of observations. 



The characteristics of this bacterium are as follows : — 



Morphologically it resembles the B. calcis already described. 



On Peptone Agar after about 36 hours at 20^ C, the colonies are 

 white in colour, circular, with a finely serrated outline and a coarsely 

 granular appearance. Superficial colonies grow very rapidly, and may 

 spread as a whitish semi-transpareut growth of irregular shape over 

 the surface of the Agar. The deep colonies remain small, globular, and 

 discrete. In old Agar cultures a brownish tinge is developed, and the 

 colour may difiuse through the substance of the Agar. On Gelatin 

 Peptone growth was rapid : in stab cultures growth proceeded from 

 the surface downwards, leaving a funnel-shaped depression of liquefied 

 Gelatin, and eventually all the Gelatin became liquefied. 



Acid formation, as shown by the Neutral Eed reaction, took place in 

 Dextrose, Mannite, and Laevulose, but not in Cane Sugar or Lactose 

 media. 



1000 C.C. of Gran's medium, inoculated on board with 10 c.c. of a sur- 

 face sample immediately after collection, and kept at an average 

 temperature of about 20' C, showed the first trace of Nitrite 

 formation after 70 hours. After 84 hours a very strong Nitrate 



