144 BOTANICAL RESULTS OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 



No. 6. Medium C. Contains short motile bacilli, mostly in pairs, others curved, 

 longer, and non-motile, a few very long vibrio-like forms, non-motile. 



After a week kept in a temperature not much above 32 F. no growth visible. 

 Transferred to laboratory 10 days later abundant nitrite ; a week later strong ammonia 

 reaction ; nitrite still present. 



No. 10. Medium H. Small actively motile bacilli ; a few larger forms. Kept in 

 laboratory. After 12 days trace of nitrite, strong ammonia. After 20 days nitrite all 

 gone, still strong ammonia. 



Nos. 11 and 12. Medium A and medium B (iGth Feb. 1903, from 62 52' S., 

 25 00' W.). Incubated in laboratory. Trace of nitrite after 8 days. Transferred to 

 60 F. Strong nitrite and slight ammonia reaction 6 days later. Presence of an 

 organism resembling Euglena, similar to that in No. 14. 



No. 14. Medium A (17th Feb. 1903, from 64 18' S., 23 09' W.). Incubated in 

 laboratory. After 15 days no nitrite reaction. Transferred to 60 F. In 7 days a 

 strong nitrite reaction, later also ammonia. No bacilli seen, but numerous rounded 

 motile bodies with a flagellum, resembling Euglena. Query Are they nitrate 

 reducers ? Later a few bacilli were seen. 



No. 17. Medium G. No growth visible after 8 days in laboratory. After 11 days, 

 at 60 F., five small white colonies appeared, which very slowly grew larger. All 

 consisted of a coccus, chiefly in diplococcus form. 



No. 19. Medium C. Grown anaerobically by Buchner's method. When opened 

 after 3 weeks tube contained a few motile bacilli, others non-motile or dead. No 

 nitrite; no ammonia. Etc., etc. 



Growth in the liquid media was usually indicated by its becoming turbid, but this 

 was always controlled by microscopic examination of hanging-drop preparation. Every- 

 one made gave + ve growths, including one anaerobically. All save three gave a definite 

 reaction of nitrite formation when tested with KI, starch, and H 2 S0 4 . Of these three, 

 one was an anaerobic culture (the only one made), the other two made from water taken, 

 not in the open sea but near the head of Scotia Bay, South Orkneys, when we settled 

 down there for winter quarters. The majority, but not all, gave later a reaction for 

 ammonia when tested with Nessler's reagent. Medium C, upon the whole, appeared to 

 be the most suitable medium for these organisms ; but the rate of growth and of 

 production of nitrite and of ammonia seemed to vary considerably, but it was always 

 very slow. In no case could I demonstrate any denitrification in tubes kept at a 

 temperature varying somewhat indeed, but never very much above 32 F. At the 

 temperature of the laboratory, varying usually between 35 F. and 55 F., 

 growth and denitrificatiou was, in most cases, proceeded with very slowly ; but when 

 incubated at a temperature kept fairly constantly about 60 F., both proceeded more 

 rapidly, although still slowly compared with results obtained in more temperate seas. 

 From these observations, therefore, it may be stated that the presence of organisms 

 with denitrifying properties seems to be fairly constant in the surface waters of the 



