40 THEOCEANFLOOR 



mounds and ridges, and bacteria in great depths. 

 Biological work with deep-sea trawls and dredges had 

 to be limited to the North Atlantic Ocean during the 

 last three months of the cruise. We also had to exclude 

 aerological work and the study of aerial "plankton," 

 that is, organic life in the higher strata of the atmos- 

 phere. It was necessary to concentrate on the sea bottom 

 and especially on its sediment carpet, which until then 



Fig. 17. The course of the "Albatross" 



was practically unknown below a depth of three feet. 



Most of the results to be reported in this book have 

 been obtained from the material gathered during this 

 cruise. Much remains unpublished and many points 

 are not definitely settled, pending investigations now 

 proceeding. I shall try to indicate the unsettled points 

 and state when the views expressed are my own and at 

 variance with those of my distinguished colleagues. 



While our expedition was under way, a series of 



