ZoBell — 34 — Marine Microbiology 



ically, by suction or differences in hydrostatic pressure, gravity, and ex- 

 plosives (Trask, 1939). In water only a few meters deep a rigid pipe can 

 be hammered into the bottom deposits, and a pile-driver form of ap- 

 paratus can be used in water two or three hundred feet deep, but neither 

 mechanism can be used for collecting samples at great depths. 



The gravity-activated coring device described by Emery and Dietz 

 (1941) can be used for collecting fairly well stratified bottom deposits 

 from any depth of water unless the bottom material is semifluid or rocky. 

 The sampler of Hjort and Ruud (1938) provides for collecting samples of 

 mud together with the water immediately above the bottom. Biologi- 

 cally this is a significant zone, it being the transitional layer between the 

 overlying water and the solid bottom. 



The Emery-Dietz (1941) coring device illustrated in Figure 4 consists 

 of a steel-pipe core barrel 2 to 2^ inches in diameter and 5 to 25 feet long 

 with a sharpened cutting nose on the bottom end and with the operating 

 mechanism attached to the top. The core nose contains a valve or core 

 retainer which is made of a short cylindrical piece of flexible celluloid cut 

 in strips in such a manner that these are pushed back against the tube 

 wall while the core is entering, but, if the core starts to slip out, the cellu- 

 loid strips close the opening as does a multiple flap valve. A large rubber 

 stopper serves as an auxiliary check valve above the core barrel. A second 

 8- to 20-foot length of pipe fastened to the top of the corer serves as a 

 shaft which has two essential functions. One is to provide a resting place 

 for enough lead disks to give a weight of 300 to 600 pounds for forcing the 

 apparatus into the bottom material. The second function of the rigid 

 shaft is to lower the center of mass of the sampler thereby increasing the 

 tendency of the core barrel to be forced into the mud in a vertical position. 

 The corer is attached to a wire cable by which the ship's winch lowers it 

 into the water. When the readings on the fathometer indicate that the 

 corer is about 300 feet from the bottom, it is allowed to fall rapidly until 

 it hits the bottom. With the Emery-Dietz corer, stratified mud cores ex- 

 ceeding 15 feet in length have been obtained from the sea floor. 



The use of a removable core-barrel liner facilitates the removal of un- 

 disturbed uncontaminated samples. Snugly fitting Incite cylinders have 

 been used as core-barrel liners. Varves and other interesting geological 

 structures can be observed through the transparent Incite finer after the 

 latter is withdrawn from the core barrel. Then, using aseptic technic, 

 samples can be removed by sawing off the tube and dissecting out radially 

 central portions for bacteriological analyses. 



Core-barrel liners consisting of 15 gauge celluloid, which is about 0.02 

 inches in thickness, have also been used. A strip of celluloid, about 8 

 inches wide and as long as the core barrel, is rolled into a cyfinder and in- 

 serted into the core barrel. After removal from the core barrel, the cellu- 

 loid liner surrounding the mud straightens out, thereby permitting the 

 observation of the material and the collection of sub-samples. When 

 washed free of adherent mud, the celluloid core-barrel liner can be used 

 again. If desirable, it can be sterilized with chemical disinfectants. 



Typical deep-sea cores collected with the apparatus described above 

 are cylinders of mud about 2 inches in diameter and 2 to 15 feet long. 

 Sub-samples for bacteriological analysis are selected from dift'erent core 

 depths by cutting through sections with previously sterilized spatulas or 

 wooden tongue blades. Using a second sterile blade, the freshly cut sur- 

 face of the core is scraped free of material which might have been intro- 



