BISTORT OF T3IE CRETACEOTJS FLINTS. 75 



thousands of square miles, .... so that it probably forms one con- 

 tinuous scum of living matter girding the whole surface of the sea- 

 bed"*. 



In 1873, according to SirWyville Thomson, "there came up, im- 

 bedded in the Atlantic ooze, an extraordinary number of siliceous 

 sponges." And referring to a dredging at a depth of 2435 fathoms, 

 " in this, as in most other dredgings in the bed of the Atlantic, 

 there was evidence of a quantity of soft gelatinous organic matter^ 

 enough to give a slight viscosity to the mud of the surface-layer. 

 If this mud be shaken with weak spirit of wine, and if a little of 

 the mud in which this viscid condition is most marked be placed in 

 a drop of sea- water under the microscope, we can usually see, after 

 a time, an irregular network of matter resembling white of qs;^, 

 distinguishable by its maintaining its outline and not mixing with 

 water. This network was seen gradually altering in form; and 

 entangled granules and foreign bodies change their relative posi- 

 tions. This gelatinous matter is therefore capable of a certain 

 amount of movement, and there can be no doubt that it manifests the 

 phenomena of a simple form of life " t. " Entangled and borne along 

 in the viscid streams of Bathybius we constantly find a multitude of 

 minute calcareous bodies " %. And again, " one of the first results 

 of deep-sea dredging was the discovery that the chalk-mud of the 

 deep sea is in many places crowded with sponges " §. 



In 1877 the same writer says, " Sponges extend to all depths ; 

 but perhaps the class attains its maximum development between 

 500 and 1000 fathoms. All the orders occur in the abyssal zone 

 except the Galcarea. At great depths the Hexactinellidae cer- 

 tainly preponderate. In the Atlantic the Hexactinellid sponges 

 are very abundant to the depths of about 1000 fathoms along the 

 coasts of Portugal and Brazil "||. "Although all the principal 

 marine Invertebrate groups are represented in the abyssal fauna, 

 the relative proportions in which they occur is pecuHar. Thus 

 MoUusca, in all their classes, Brachyourous Crustacea, and Anne- 

 lids are on the whole scarce ; while Echinodermata and Porifera 

 greatly preponderate " %. 



We have now to look upon another side of this singularly phan- 

 tasmagorian picture. Here is what Mr. Murray, of the ' Challenger,' 

 stated on the subject in his report dated 1876, based on the re- 

 searches of Mr. Buchanan : — " In the early part of the cruise many 

 attempts were made by all the naturalists to determine the presence 

 of free protoplasm in, or on, the bottoms from our soundings and 

 dredgings, but with no definite result. It was undoubted, how- 

 ever, that some specimens of the sea-bottom preserved in spirit 

 assumed a very mobile or jelly-like aspect, and also that flocculent 



* Speech by Prof. Huxley, following the reading of a paper " On the Atlantic 

 and Indian Oceans," by Capt. Sherard Osborn, E.N. (Proc. Eoy. Geograph. 

 Soc. for November 1870, p. 38). 



t ' Depths of the Sea,' p. 410. + Ibid. p. 413. § Ibid. p. 483. 



11 ' The Atlantic,' by Sir Wyrille Thomson, 1877, vol. ii. p. 343. 



^ Ibid. pp. 352, 353. 



