34 



Papers from the Marine Biological Laboratory at Tortugas. 



shore a good deal of organic matter was present, chiefly in the form of de- 

 caying mangrove roots. Farther out from the shore little organic matter 

 was noticeable, but it was not possible to examine the deeper layers of the 

 mud in these situations. The only organic matter that was seen consisted 

 of the rootlets of a species of Zostera, found in occasional patches some miles 

 ofif the coast. 



BACTERIAL INVESTIGATIONS IN THE DEEP WATER OF 

 THE TONGUE OF THE OCEAN. 



Continued bad weather during the whole of our stay at Andros greatly 

 added to the difficulties of this work, and on this account it was only found 

 possible to work three stations. The last two were worked under the most 

 disadvantageous conditions, the quick roll of the boat making the filling 

 of the water-bottle with alcohol and the siphoning off of the sample under 

 sterile conditions a matter of the greatest difficulty. 



The first station worked was 6 miles due east of Golding Cay, the second 

 14 miles east of Golding Cay, and the third 10 miles ENE.J^E. of Golding 

 Cay. The three stations were thus at the angles of a triangle which was 

 nearly equilateral, the base being a little longer than the sides and running 

 due east and west. 



At the first station, worked on May 8, bottom was sounded at 822 

 fathoms. The sea was calm at first, with a SSE. swell, but became choppy 

 later. The wind was SSE., force o to i, at 8*'30™ a.m., freshening to about 

 force 3 at 10^30™ a.m. The sample of the bottom obtained by the snapper- 

 rod was of a very stiff clay-like consistency, grayish white in color, and was 

 composed of very minute unorganized particles of calcium carbonate 

 containing a few pteropod and globigerina shells. The following tempera- 

 tures, to which the necessary corrections have been applied, were recorded: 



Depth. Temperature. 



Fms. I °C. 



Surface 26.90 



10 j 25.90 



SO i 25.14 



100 1 22.00 



200 i 1713 



Depth. 



Fms. 



400 



600 



Bottom (822 fms.) 



Temperature. 



|§;°^}average = 8.98 



{4.62}^^^''^^^ =4-70 

 {l;^^} average =3.97 



These samples, without previous dilution, were plated in peptone agar, 

 I c.c. of the sample being used for each plate. The agar was cooled to just 

 under 40° C. before plating. It is very necessary that this temperature 

 should not be exceeded, as many marine bacteria are very sensitive to heat; 

 the use of agar at as high a temperature as 45° C. will cause the death of a 

 large proportion of the bacteria, though in the process of plating they can 

 be exposed to this temperature only for a very short time. The cultures 

 were kept in the dark at the room temperature (averaging about 28° C.) 

 and at the end of 24 hours a free growth of colonies was apparent. At the 

 end of 48 hours the plates were counted with the following results : 



