63 



taking place under wat?r; a substance so resistant to ordinary 

 bacteria that it is commonly used in the laboratory as an indiffer- 

 ent substance for solidifying culture mi'dia. The agar liquifying 

 organisms now knojvn have actually come from sea water, but the con- 

 ditions necessary for their growth do not seem to prevail in the 

 ocean. Is this a case of bacterial action at all, or does the 

 annual disintegration of millions of tons of kelp, etc. simply 

 reflect the solvent action of the sea water itself? We face this 

 same problem with regard to the destruction of the chitin in the 

 shells of dead crabs, shrimps, and other crustacean. Benecke's 

 Bacillus chitinivorus will digest chitin in the laboratory, but 

 apparently not under conditions met with in the sea. 



All this bears on the composition and structure of these 

 refractory organic compounds, whose constitution is still chemically 

 unknown. It msy be possible, by m:^ans of the organisms that attack 

 agar and chitin to unravel the composition of the latter, and during 

 the breakdown to recover substances of commercial value. 



How, too, is the oil destroyed, that is formed by diatoms, 

 algae, Copepods, etc.? Poes it undergo fermentation through aner- 

 obic organisms to hydrogen caroons in the bottom muds, or is it 

 oxidized as in the animal organisms? 



Bacteria also play other important roles, of which we, as yet, 

 have only glimpses, in the chemical changes following the altera- 

 tion and decomposition of organic matter that takes place in the 

 deepest water and in the bottom sediments. Here we think at once of 

 the for.ns that reduce sulphates in the absence of oxygen to sulphides, 

 of whose activities the vast deposits of stinking mud in shoal 

 waters (especially in enclosed basins with little circulation) bear 

 witness. Bacteria, too, ere indirectly responsible for the accumu- 

 lation of sulphurated hydrogen in the deeps of the Black Sea and of 

 certain fjords. 'He greatly desire more detailed Bacterio-chemical 

 studies of the deep water of other such basins, e.g. of the Sulu 

 Sea. The activity of these same groups needs to be studied in the 

 open ocean, where, becaust: of the active circulation of the water, 

 their effects are not so apparent. We know almost nothing aoout the 

 rSle bacteria play in other chemical changes that take place in the 

 abyssal muds. 



The whole question of calcium precipitation in the sea is still 

 an open one, and one so im.portant that it is now being made a major 

 subject of investigation at the Scripps Institution. But this 

 necessarily involves companion studies of the physioco-chemical 

 relationships in the sea water, to show what chemical changes such 

 precipitation involves. When this is known it will not be enough to 

 find out whether bacteria can bring these changes about; we must 

 also learn whether they are associated with the mass precipitations 

 in the sea in significant numbers; also whether there is sufficient 

 nutrient in these situations to support their growth. The necessity 

 for uniting several disciplines in this esse illustrates how bread a 

 view we must take of bio-physical and bio-chemical problems as a. 

 whole in the ocean. 



A few more live problems that have a general bearing both on 

 bacteriology per se and on the science of the ocean, may be mention- 

 ed. What, for instance, are the energy relationships in the sea, the 



