DEPTHS IN THE NORTH ATLANTIC OCEAN. 205 



** an independent kind of organism, related to, but not the 

 mere rudimentary form of, Foraminifera." 



" With respect to the coccoKths, their optical character 

 proves that they have an extremely fine, radiating, crystalline 

 structure, as if they had gi-own by the deposition of car- 

 bonate of lime on an elongated central nucleus, in accordance 

 with the oval-ringed structure shown in fig. 1 (magnified 

 800 linear)." 



I am not aware that anything has been added to our 

 knowledge of the " coccoliths" and " coccospheres" since the 

 publication of Mr. Sorby's and Dr. Wallich's researches. 

 Quite recently I have had occasion to re-examine specimens 

 of Atlantic mud, which were placed inspirits in 1857, and 

 have since remained in my possession. I have employed 

 higher magnifying powers than I formerly w^orked with, or 

 than subsequent observers seem to have used, my great help 

 having been an excellent -Vth by Ross, which easily gives a 

 magnifying power of 1200 diameters, and renders obvious 

 many details hardly decipherable with the -g^th inch objective 

 which I used in 1857. 



The sticky or viscid character of the fresh mud from the 

 bottom of the Atlantic is noted by Captain Dayman.* 

 " Between the 15th and 45th degrees of west longitude lies 

 the deepest part of the ocean, the bottom of which is almost 

 wholly composed of the same kind of soft, mealy substance, 

 which, for want of a better name, I have called ooze. This 

 substance is remarkably sticky, having been found to adhere 

 to the sounding rod and line (as has been stated above) 

 through its passage from the bottom to the surfjice — in some 

 instances from a depth of more than 2000 fathoms." 



This stickiness of the deep-sea mud arises, I suppose, from 

 the circumstance that, in addition to the Globigerina of all 

 sizes which are its chief constituents, it contains innumer- 

 able lumps of a transparent, gelatinous substance. These 

 lumps are of all sizes, from patches visible with the naked eye 

 to excessively minute particles. When one of these is sub- 

 mitted to microscopical analysis it exhibits — imbedded in a 

 transparent, colourless, and structureless matrix — granules, 

 coccoliths, and foreign bodies. 



The granules vary in size from ^f-fJj-jj^th of an inch to 

 "s o' oo ^^? ^^^ ^''® aggregated together into heaps of various sizes 

 and shapes (PI. IV, fig. 1), some having the form of mere irre- 

 gular streaks, but others possessing a more definitely limited 



* Loo. cit., p. 9. 



