16 president's address. 



ooze, a calcareous deposit, is abundant in equatorial seas, while in the 

 Antarctic the characteristic deposit is siliceous Diatomaceous ooze. 



The part played by bacteria in the metabolism of the sea is very 

 important and probably of wide-reaching effect, but we still know very 

 little about it. A most promising young Cambridge biologist, the late 

 Mr. G. Harold Drew, now unfortunately lost to science, had already 

 done notable work at Jamaica and at Tortugas, Florida, on the effects 

 produced by a bacillus which is found in the surface waters of these 

 shallow tropical seas and in the mud at the bottom ; and which denitrifies 

 nitrates and nitrites, giving off free nitrogen. He found that this 

 Bacillus colds also caused the precipitation of soluble calcium salts 

 in the form of calcium carbonate (' drewite ') on a large scale, in the 

 warm shallow waters. Drew's observations tend to show that the 

 great calcareous deposits of Florida and the Bahamas previously known 

 as ' coral muds ' are not, as was supposed by Murray and others, 

 derived from broken-up corals, shells, nullipores, &c., but are minute 

 particles of carbonate of lime which have been precipitated by the 

 action of these bacteria.^" 



The bearing of these observations upon the formation of oolitic 

 limestones and the fine-grained unfossiliferous Lower Palaeozoic lime- 

 stones of New York State, recently studied in this connection by E. M. 

 Field,'' must be of peculiar interest to geologists, and foiTns a notable 

 instance of the annectant character of Oceanography, bringing the 

 metabolism of living organisms in the modern sea into relation with 

 palaeozoic rocks. 



The work of marine biologists on the plankton has been in the 

 main qualitative, the identification of species, the observation of struc- 

 ture, and the tracing of life-histories. The oceanographer adds to that 

 the quantitative aspect when he attempts to estimate numbers and 

 masses per unit volume of water or of area. Let me lay before you 

 a few thoughts in regard to some such attempts, mainly for the 

 purpose of showing the difficulties of the investigation. Modern quanti- 

 tative methods owe their origin to the ingenious and laborious work 

 of Victor Hensen, followed by Brandt, Apstein, Lohmann, and others 

 of the Kiel school of quantitative planktologists. We may take their 

 well-known estimations of fish eggs in the North Sea as an example 

 of the method. 



The floating eggs and embryos of our more important food fishes 

 may occur in quantities in the plankton during certain months in 

 spring, and Hensen and Apstein have made some notable calculations 



" Journ. Mar. Biol. Assoc, October 1911. 



» Carnpgie Institute of Washington., Year Book for 1919, p. 197, 



