Chapter III — 39 — Collecting Samples at Sea 



the conclusion be warranted that there are no bacterial species in the sea 

 which are injured by the temperature changes which occur during the col- 

 lection of samples. If there are such supersensitive bacteria in the sea, 

 certainly they are in the minority because as many bacteria are demon- 

 strable in deep sea deposits subjected to temperatures of 20° C. as in 

 warmer shallow water deposits similarly treated. 



The examination of samples at sea : — The preparation of materials 

 for bacteriological work at sea requires careful planning. For obvious 

 reasons it is necessary to take everything aboard the boat that will be 

 needed for the examination of samples while on the cruise, and even the 

 largest and best equipped research vessels provide only limited space for 

 laboratory supplies. The microbiologist who has ten square feet of lab- 

 oratory space and twenty cubic feet of storage space on a research vessel 

 may feel relatively fortunate. 



Due to the pitch, roll, vibration, and other movements of the vessel, 

 the microbiologist will find it convenient to have a stationary stool upon 

 which he can steady himself with his legs or with a strap so that both 

 hands can be free to work. The stool should be so located that everything 

 needed for the examination of samples is within arm's reach. Ledges 

 around the edges of the laboratory desk and shelves will help to prevent 

 equipment from roUing or sliding off. Special flat-bottomed holders must 

 be provided for pipettes, test tubes, reagent bottles, and other equipment 

 in order to prevent spillage and breakage. For this purpose holes of the 

 correct diameter drilled into blocks of wood two inches thick are useful. 

 The blocks can be secured to the laboratory table in the most convenient 

 location. Wooden boxes designed to fit the available space in the vessel 

 and to accommodate snugly the glassware provide for the storage and 

 transport of equipment. 



An alcohol burner can be used to sterilize inoculating needles and to 

 flame the mouths of culture receptacles. While it is recommended that 

 as much glassware and media be sterilized as possible before embarking, 

 the galley oven and a pressure cooker can be used for the sterilization of 

 glassware and media while at sea. Even on poorly equipped boats, ma- 

 terials can be sterilized in a pressure cooker over a primus or other burner. 



Experiencing difficulty pouring Petri dishes in rough weather at sea 

 and finding that a platform hung on gimbals failed to provide the neces- 

 sary stabihty, Gee (1932c) recommended the use of a mechanical spinner 

 for preparing Esmarch cultures. Melted nutrient agar cooled to 42° to 

 45° C. in large test tubes was inoculated with i.o ml. of appropriately 

 diluted material, after which the tube was rapidly rotated mechanically 

 until the agar solidified in a thin layer on the walls of the tube. After a few 

 days of incubation the colonies which develop can be counted and picked 

 for further study. While this ingenious device achieves its intended pur- 

 pose, it greatly complicates the preparation of cultures for counting. 



Flat-sided six-ounce medicine or prescription bottles have proved to be 

 superior to either Petri dishes or Gee-Esmarch tubes for plating samples 

 at sea for colony counts. After introducing 20 to 25 ml. of nutrient agar, 

 the prescription bottles can be stored in quantity with the screw-top caps 

 tightly closed until they are needed. Then after melting the agar, they 

 are cooled to 42° to 45° C. in a water bath and inoculated with appropri- 

 ately diluted sea water or mud. Immediately after receiving the inoculum 

 the bottles must be plunged up to the neck into cold water for an instant 



