THE BIOLOGICAL AND CHEMICAL PROGRAM 



The biological and chemical program of the Carnegie 

 consisted chiefly of marine microbiology, the study of 

 planktonic organisms, and the nature of their environ- 

 ment; but dredgings in shallow water and shore collec- 

 tions of a general biological nature were made when the 

 opportunity afforded. Owing to the lack of time and of 

 space for dredging equipment, the collections at sea nec- 

 essarily were restricted to planktonic organisms. Ef- 

 forts were made to obtain a vertical section of the plank- 

 ton population at each station and to obtain the necessary 

 physical and chemical data for the study of the many fac- 

 tors which govern the distribution of the plankton 

 throughout the seas. Plankton samples of the upper 100- 

 meter layer were taken at each station at depths approx- 

 imately 0, 50, and 100 meters. 



Samples were collected for both systematic and 

 quantitative studies; the qualitative samples with silk 

 townets, and the quantitative with a Pettersson plankton 

 pump. The nets were made of silk bolting-cloth con- 

 structed as described by Seiwell (1), in two sizes, name- 

 ly, one meter, and one-half meter in diameter. The nets 

 originally were towed astern during an oceanographic 

 station; but because of frequent fouling with other wires 

 that were run astern, later they were lowered from the 

 bow where entanglement with other wires was not so 

 likely. The nets were towed with stranded 6-mm alumi- 

 num bronze wire payed out from a hand reel on the quar- 

 ter-deck and snubbed around the after bit. They were 

 hauled in with the electric winch by taking a few turns of 

 the wire around a revolving gypsyhead. In lowering the 

 nets, a lead weighing about seventy pounds was attached 

 to the end of the wire and lowered below the surface. 

 Nets were placed at various intervals along this line by 

 tying the bridles to the wire above split and hinged brass 

 balls clamped to the wire. It was customary to take 

 samples at the surface and at depths of 50 and 100 me- 

 ters, with an occasional vertical haul from a depth of 150 

 meters. A table was compiled, giving the lengths of line 

 necessary to lower the nets to the desired depths with 

 different wire angles. Before lowering the nets, the angle 

 on some other line--the pump line, for example--was 

 measured and the expected angle on the net line was 

 judged. From the table, the length of tow line required 

 could be obtained which would lower the nets to the ap- 

 proximate depths. The surface net was towed from a 

 separate line. The meter nets were used only in good 

 weather since they offered so much resistance to the 

 water that the strain produced by the pitching of the ves- 

 sel was sxifficient to tear them in rough seas. Half- 

 meter nets were used in bad weather, although these, 

 too, often were torn by severe surging of the vessel in 

 heavy seas. Much of this trouble was obviated and the 

 life of the nets increased by the use of airplane shock- 

 absorber cord on the net bridles of the surface net and 

 on the end of the wire of the other nets after the latter 

 had been lowered to their proper levels. At the begin- 

 ning of the cruise, closing nets were used to eliminate 

 contamination from upper layers, but these were aban- 

 doned owing to trouble with the closing devices and to the 

 fact that quantitative samples were being secured with 

 the pump. 



The Pettersson plankton pump was used regularly 



for collecting quantitative samples. It was operated at 

 the same depths at which the net tows were made so that 

 a check on the two hauls was obtained and a picture of 

 the life at those levels might be more easily drawn. 

 Trouble with the operation of the pump was experienced 

 because of its complicated mechanism and a great many 

 adjustments had to be made. When these difficulties were 

 overcome (temporarily on each occasion) the results 

 were quite satisfactory, but several important changes 

 in design should be made to secure a consistently prac- 

 tical piece of equipment. 



Quantitative samples also were obtained by collect- 

 ing water in an Allen bottle as well as in a Meteor bottle 

 and straining the water through a silk filter net. The 

 results so obtained were compared with those of the 

 pump and it was found that where the water is as scanti- 

 ly populated as it usually is far out at sea, a greater 

 quantity of water than is collected in these bottles must 

 be strained. The advantage of the Pettersson pump lies 

 in the larger quantity of water filtered. During the lat- 

 ter part of the cruise some surface samples for phyto- 

 plankton were taken after the method of W. E. Allen, by 

 passing twenty liters of water through a filter net, the 

 water being collected in a draw bucket over the side of 

 the vessel while under way. 



For collecting larger floating organisms a dip net, 

 equipped with a handle five meters long, was used. To 

 facilitate the use of this net and of the surface tow nets 

 while the vessel was under way, a special boom walk 

 was installed on the starboard forward side where the 

 collector might walk nine meters out from the side of 

 the ship and drag the nets well beyond the wash of the 

 vessel. This walk, however, was seldom used because 

 it was impractical when the vessel was rolling appreci- 

 ably and townets could not be used when the vessel was 

 making much headway. 



The oceanographic laboratory had complete micro- 

 scopic equipment so that an examination of the plankton 

 samples could be made at the time of collecting. Time 

 did not permit of a critical study on board but examina- 

 tions were made to determine the general characteris- 

 tics of the region being traversed and to compare results 

 obtained by different collecting methods. 



The plankton samples were preserved in 8-ounce 

 and 16-ounce wide-mouthed bottles as used by the U.S. 

 Bureau of Fisheries. Formaldehyde was the preserva- 

 tive used, borax sometimes being added for the preser- 

 vation of calcareous specimens as described by Atkins 

 (2). Flemming fluid was used also. 



Every two or three months (the intervals being 

 governed by the shipping facilities of ports) the samples 

 accumulated on board were shipped back to the office of 

 the Department of Terrestrial Magnetism, at Washing- 

 ton, to await further study. Before shipping, each bottle 

 was tightly corked and the tops sealed over with viscose 

 or cellulose self-fixing caps (3) which prevented any 

 evaporation of the fixative during transit or while in 

 storage at the office. 



In shallow waters (usually when the ship was in port 

 and work was done with the launch) dredgings were made 

 for bottom-living diatoms and foraminifera. A Mann 

 diatom bucket dredge was used for this purpose. For 



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