416 Marine Microbiology 



sponsible for these processes from the numerous other species 

 which developed in Omehansky's medium. 



In practice we seeded 20 g of marine ooze or sand in 400 

 ml of Omeliansky medium. It is certain that this medium, con- 

 taining no source of organic carbon, selects autotrophic bacteria, 

 but even so, the possibility of development of other bacteria due 

 to the presence of organic material carried with the inoculum 

 cannot be overlooked. 



Nitrite appearing in the medium was titrated with Griess 

 reagent, and nitrate by the sulfophenic reaction. The results ob- 

 tained at different time intervals are expressed in micrograms 

 of nitrous or nitric nitrogen per 10 ml of culture medium. 



DESCRIPTION OF SPECIMENS STUDIED 



Geographic Distribution 



The 44 samples studied were taken quite near the Algerian 

 coast. Actually we had available marine muds taken by the 

 laboratory of "Algerian Marine Station" from the bay of Algiers 

 itself, or from the area around tliis bay. These samples were col- 

 lected under the direction of Professor Bernard during a system- 

 atic exploration of the ocean depth in the bay of Algiers (geo- 

 graphic location is: 3° to 3°30' east and the line 36°52' north 

 of the bay of Algiers). The depth explored extends from 50 to 

 1,000 m. 



We also collected sands originating from the rather special 

 sedimentary formation abundantly represented around the "Casti- 

 glione Station of Agriculture and Fishery." This fonuation, locally 

 called "Mattes," constituted almost entirely of sands, is set in a 

 substratum with a covering of vegetation consisting of Zostera 

 and Cymodocacae (2). It consists of a sort of littoral marine basin 

 covered by a thin sheet of water and is dry under certain atmos- 

 pheric conditions (east wind, high barometric pressure). 



In the deep areas a gravitv corer was used. In the shallow 

 basin we took advantage of dry periods and operated as for land, 

 with a core sampler or a dredge. From the center of the plug 

 thus obtained, or from the block taken up by the dredge, we took 

 samples with a sterile scoop; the specimens then being stored 



