146 BOTANICAL RESULTS OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 



4. Same as No. 3, but medium consists simply of gelatine, 10 grin., sea water 



100 c.c. Incubated in laboratory. 

 Result, 112 colonies. 



5. Water from 2000 fathoms, 6th March 1903, lat. 67 39' S., long. 36 10' W. 



Out of Buchanan-Richard water-bottle. Medium G. Inoculated Petri dish 

 with 5 - 2 c.c. of the water. Incubated at 60 F. 



Result, 2 colonies. 



Could not absolutely exclude contamination from surface waters. The growths 

 consisted of small motile bacilli. 



6. Water from 2485 fathoms (15 fathoms above the bottom), 6th March 1903, 



lat. 67 39' S., long. 36 10' W. Out of Buchanan-Richard water-bottle. 

 Medium G. 5 '3 c.c. water inoculated. Incubated at 60 F. 



Result, 1 colony. 



Here, also, surface contamination could not be absolutely excluded. The growth 

 was of a very minute motile bacillus, which produced slight liquefaction of the 

 gelatine. Sub-culture in medium C was sterile. 



Three of the four estimations of surface water, yielding respectively 170, 334, and 

 35 colonies per c.c. of water, were made on media suitable for denitrifying organisms, 

 so are not comparable with the results obtained by Dr Gazert and Dr Ekelof, who, on 

 ordinary media, never obtained more than 21 colonies per c.c., and usually a much 

 smaller number. One observation made on sea- water gelatine yielded 112 colonies 

 from 1 c.c. of water. I can offer no explanation for this difference in results. It may 

 be that the surface water of the open Weddell Sea is really more rich in bacteria than 

 the waters nearer inshore, such as were examined by Dr Ekelof Those examined by 

 Dr Gazert, however, cover a much wider area of sea, much of it open ocean. It is not 

 fair to judge, of course, from one isolated observation, but so far as I am aware there was 

 no error in my technique, and I can only leave the figure to stand for future corroboration 

 or disproof. 



(d) Examination of Deep-sea Samples for the Presence of Bacteria. 



Sixteen samples of bottom mud, bottom water from the Buchanan sounding tube, 

 and of waters from various intermediate depths from 100 fathoms downwards, taken 

 from Buchanan-Richard or Nansen-Petersen water-bottles, were examined, all from the 

 Weddell Sea area. From 5 to 10 c.c. were inoculated in tubes or Petri plates, the media 

 used being G (chiefly), C, A, and B (see under "Denitrifying Bacteria"). They were 

 incubated either in the laboratory (temperature 35 F. to 55 F.) or at 60 F. The con- 

 ditions under which the samples were obtained did not absolutely preclude surface water 

 contaminations, but the results do not look as if this had occurred, for of the sixteen 

 only three yielded any growth. Two of these, on medium G, are referred to in more 

 detail above under " Quantitative Estimations." rather over 5 c.c. of water in each case 

 yielding respectively 2 colonies and 1 colony. The third was an inoculation of water 



