64 



thermophilic associations, end pigment function of the widespread 

 purple bacteria? Wh?t r6''le is played by the luminous bacteria, 

 whether as saprophytes or as normal symbionts with animals and 

 plants? Do these bact^rin exist at absyssal depths? If so, are 

 they sufficiently abundant for their luminescence to be important 

 in the vital economy of deep sea animals? To they, perhaps, help 

 to make vision possible for the large eyed benthonic fishes of the 

 abyss, most of which are non-luminous thems^'lves? 



The marine anaerobes have received scsnt attention. Here the 

 recent discovery that CO2 tension rather then oxygen tension is the 

 requirement th^t distinguishes them from aerobes, emphasized txhe 

 necessity for further information as to chemical conditions in the 

 water. 



k bacteriophage has also been found in the sea by French ocean- 

 ographers. How generally this principle (destructive to bacteria) 

 is distributed in the sea, and how effectively it combats their 

 manifold activities th^r, if at all, remains to be leerned. 



Finally it should be said that microorganisms other than 

 bacteria have been found in the ocean and that they may have a 

 quantitative importance in the chemical processes th'jt have been 

 enumerated, comparable to that of the bacteria proper. This rela- 

 tionship has been well ■established in the case of soil micro-biology. 

 The Actinomyces may bs cited as a group that are as -worthy of 

 attention es are the bact-ria themselves. 



The answers to the principal questions that the oceanographer 

 may properly ask of the bacteriologist are not as directly available 

 as their mere enumeration might suggest; for it seems certain that 

 no great headway can be made toward appr-cietinsc the role of bacter- 

 ia are perfected. 



No on- instrament will solv-.: the proolem of bacteriological 

 sampling in the sea. For purposes of enumeration the sample must 

 be large and not necessarily taken with utmost bacterial precaution. 

 Concentrating the sample prior to microscopic enum.eration is a more 

 difficult task. It would appear that a sound procedure for this 

 purpose has been introduced in Russia primarily for fresh water 

 work, but capable of adaptation to the sea. Th= sampling of water 

 for culture work, when small volumes suffice, presents few obstacles. 

 More difficult is the sampling of mud for in this case it is neces- 

 sary to recover an undistrubed specimen so that the sample can be 

 examined serially, commencing for example with the top millimeter, 

 unmixed with lower layers and unwashed by superposed water on the 

 asc ent . 



And it should, in general, be emphasized that random procedure, 

 and approximate technic can never serve as the basis for evaluating 

 the general shar^ of bacteria in the economy of the sea. We have 

 also to learn what modifications of the routine media, or of those 

 favorable for soil organisms, will give the maximum counts of 

 bacteria from a given sample of ocean water. We shall not be able 

 to assay the significance that should be attached to the physiologi- 

 cal activity of marine bacteria until we are able to grow most of" 

 the organisms th^t can be found in the water. The f^^ct that this 

 will certainly require study both of pure and of m.ixed cultures is 



