Ndl - 



AN 1 \UCTII BACTI IU'l "<iY 



147 



out of a Buchanan wat-r-l><>ttlr from a depth of 2550 fathom*, i.e. bottom water 

 (If.tli M.in-li 1903, Int. 63 51' 3., long. 41 50' W.), on medium F (described under 

 N untying Organisms"), the only sample tru-.i m this medium. Inoculations of water 

 from the same sample in mlia A and B proved sterile, l>ut in K there grew very slowly 

 a short inutile Imcilliis, occurring singly, in couples, and also in short chains, the chain 

 formation being more pronounced than in any other marine bacterial growth which I 

 obtained No ammonia or nitrate was formed in the medium. 



Dr Gazert, in waters down to 800 metres deep, found germs absent or very few in 

 number (from 1 to 3 in 10 c.c.). Bottom-water samples were either sterile or yielded 

 from 3 to 6 bacteria in 10 c.c. Ooze water, i.f. the layer of water just touching 

 the bottom, was not so often germ-free. The oozes and muds themselves appear to be 

 always sterile. Nitrifying and denitrifying organisms were not found in any of his 

 deep-sea samples. 



(e) Examination of Sta Water for Nitrifying Organisms. 



The media employed as suitable for the growth of nitrite- and nitrate-forming 

 organisms were as follows : 



Five inoculations were made in each medium with surface water from various parts 

 of the Weddell Sea area, during February 1903, but in no case save one did any growth 

 occur after incubation at varying temperatures between 32 F. and 60 F. In one 

 instance a slight growth occurred in an inoculated tube of medium F, but the organism 

 was evidently a denitrifier and not a nitrifier, for ammonia was found but no nitrate. 



One deep-water sample inoculated in medium F also gave a growth, but neither 

 ammonia nor nitrate was found in this instance (see under " Deep-Sea Samples "). 



The conclusion to be drawn seems to be either that nitrifying organisms are not 

 present in these waters, or that the media employed were not suitable for their growth. 



Dr Gazert, using Winogradski's medium (without silicate), also failed to get any 

 evidence of nitrification going on through the action of bacteria in Antarctic waters. 



3. AIR EXAMINATION FOR THK PRESENCE OF BACTERIA. 



Several examinations were made by exposing plates of agar and of medium G (for 

 denitrifying organisms) on the top of the deck laboratory during the voyage in the 

 Weddell Sea in 1903. These cannot be considered satisfactory, owing to the possibility 



