1754 AGRICULTURAL BOTANY, CHEMISTRY AND PHYSIOLOGY OF PLANTS 



full report of the bacteriological work acconii)lished on this expedition has 

 recently been published by the Russian Department of Agriculture (i) 

 and the present paper merely summarises the report. 



The bacteria in the Arctic Ocean were investigated in order to deter- 

 mine their influence, direct or indirect, on the organic life of the ocean, 

 In 1890-1891, investigations of a similar nature were already being cariied 

 out by Russians in the Black Sea and the production of sulphuretted hy- 

 drogen was observed. But with regard to the northern waters, though there 

 were grounds for believing that they contained an actiw bacterial flora, 

 actual experimental data was very scarce. In 1899 some results were pub- 

 lished stating that from 11 cc of water only one colony had been obtained. 

 In 1907 investigations were begun in the waters of the South Pole, but 

 these hardly dealt with the action of specific organisms. Nevertheless it 

 was the results of these experiments together with the fact that denitri- 

 fication does not usualh^ take place at temperatures much below about 

 20^ C. which gave rise to the theory known as Brandt's hypothesis, i. e. that 

 the distribution of plankton in the ocean is controlled by the supply of 

 combined nitrogen according to Liebeg's Law of the Mininmm and that 

 the combined nitrogen in its turn is dependent on the activity of the deni- 

 trifying organism; therefore that the relative abundance of plankton in 

 the arctic seas compared with warmer waters is due to the absence of de- 

 nitrifying bacteria. 



In the Murman expedition Clostridium and Azotuhader were isolated 

 from the mucilaginous surface of seaweed on which they live and from which 

 they draw the necessar^^ energy for growth and nitrogen fixation. Both 

 organisms developed best in media containing sea salt. In sea water as in 

 soil they were always accompanied b}' Winogradski's a and ^ bacilli. It 

 would appear that a certain amount of symbiosis must occur between the 

 nitrogen fixing organisms and the seaweed and that the organisms provide 

 a very useful addition to the seaweed's food supply, given the natural de- 

 ficiency of nitrogen in sea water. 



Though nitrifying bacteria were found in the Gulf Stream at yi° lat. 

 north near lekaterininsk and in the Ugorskij Sharr, their presence in arc- 

 tic seas is still unproved. It is pointed out that the low temperature, which 

 might be looked upon as causing complete inhibition, while it slows 

 down the process of nitrification, never entirely stops it even at 2*^ C. 



Denitrifying bacteria were found fairh- abundantly in the Arctic 

 Ocean and they were studied in some detail. Kven after four years, 

 cultures of non spore-forming bacteria retained the power of decomposing 

 nitrates and setting free nitrogen. Under perfectly anaerobic conditions 



(i) B. JI. HcAHEHKO, Hscji-fejiiOBaHia na.n'B 6aKTepijiMn C'feBepHaro JIe/i;oBi-i- 

 Taro OKcana. C'i> 3 Ta6jiiiu,aMii 11 63 pncyHKaMn I — Vil -(- 297 cxp. (Tpyjiu 

 MypMaHCKoii HayiHO-IIpoMbicjiOBoii BKcneAnuiii 1906 ro.n;a. H3jtaHie /Jtenap- 

 TaMeHxa SeMJie^'fejiiH. neTporpaAi>. 1914)- [Issatchenko B. L., Research on the 

 bacteria of the glacial Arctic Ocean, 297 pp., in Report of the Scientific and industrial expe- 

 dition of Murman (1906). Petrograd, 1914). 



