FROM THE NORTH SEA. 123 



soda did not completely remove the adherent mud from the sand- 

 grains and foraminifera. 



This is a noticeable feature, because as a rule muddy dredgings 

 are readily broken down if thoroughly dried before the cleaning 

 process is commenced, and even the most stubborn muds generally 

 succumb to the action of boiling soda. 



We have, however, met with similarly refractory muds at a few 

 of the " Goldseeker" stations in the Moray Firth, and are unable 

 to satisfy ourselves as to the cause of this viscosity, which is 

 quite possibly due to different causes in separate localities. 

 Among the various explanations which have occurred to us are : 



1. The presence of the Hag (Myxine glutinosa). This loath- 

 some fish is very common at some of the " Goldseeker " stations 

 where the viscosity has been observed, and as when captured 

 or touched it exudes an incredible quantity of slime, it is quite 

 possible that the presence of this fish in any numbers might 

 locally influence the nature of the sea-bottom. But Mr. Borley 

 tells us that Myxine is rare in the vicinity of the Stations 

 sampled, so it may be dismissed from consideration so far as the 

 " Huxley " material is concerned. 



2. Chemical changes in the mud owing to its having passed 

 through the digestive organs of worms and Echinoderms, many 

 of which obtain their nutriment by swallowing mud and extract- 

 ing the organic matter. Thus, in the deep water of some of the 

 Norwegian fjords, the bottom deposit consists of a very fine 

 mud full of the tests of rhizopods and swarming with Annelids. 

 When the mud is dried and broken down again in water, and 

 the foraminifera have been removed by floating and elutriation, 

 a mass of fine granular material is left which under the micro- 

 scope proves to consist of small oval pellets of mud, the excreta 

 of worms (PL 11, fig. 2).* These pellets resist the action of 

 soda, making it evident that the mud must have become altered, 



* Such deposits are presumably similar to those referred to by Dr. Johan 

 Hjort under the name of "coprolitic muds." See The Depths of the Ocean, 

 by Dr. J. Hjort and Sir John Murray (1912), p. 148. 



