Feb. 3, 1881] 



NA TURE 



!25 



diversified in the one case by oceanic currents on the surface as 

 well as on the bottom, and in the other by foaming rivers and 

 gentle streams . I will give a few instances of such inequalities 

 in the North Atlantic. Wliile repairing in 1S7S the Anglo- 

 American Cable, a tract of rocky ground was discovered, about 

 100 miles in length, in tlie middle of the North Atlantic, be- 

 tween 33" 50' and 36° 30' West longitude, and about 51" 20' 

 North latitude. Within a distance of eight miles the shallowest 

 sounding was 1370, and the deeiaest 2230 fathoms, a dift'erence 

 of 860 fathoms, or 5160 feet ; » ithin four miles the difference was 

 3180 feet, and within half a mJe 1380 feet. There are also the 

 Laura Ethel Bank, with a depth of only 36 fathoms, and the 

 Milne Bank, with 81 fathoms, both about 550 miles from New- 

 foundland, which is the nearest continental land. Other in- 

 stances are the Josephine Bunk, with 82 fathoms, and Gettysburg 

 Banl;, with 30 fathoms, the distance of the former from Cape 

 St. Vincent being 250, and the latter 130 miles, with inter- 

 mediate depths of from 1700 to 2500 fathoms. The soundings 

 in the Bulldog Expedition also gave 748 between u6S and 1260 

 fathoms, and the Valorous soundings gave 690 between 1450 and 

 1230 fathoms in another part of the North Atlantic and very far 

 from any land. 



A glance at the large series of diagrams of the Challenger 

 soundings will at once serve to convince one of the extreme 

 • unevenness of the sea-bottom eveiywhere in the Atlantic and 

 Pacific oceans. It would be difficult to find a greater degree of 

 unevenness in any diagrams of the earth's surface, the total 

 extent of which scarcely exceeds one fourth of that of the sea. 



Diagrams to illustrate the inequalities of the sea-bottom in the 

 case of the telegraph cable, and the irregularities of level in a 

 similar extent of land in the Perthshire Highland.^;, are placed 

 before you. 



9. Deposits. — The floor of the ocean is covered by a more or 

 less thick layer of ooze or mud, and of clays of different sorts and 

 colours, which is inhabited by various animals. One of these 

 deposits is called " Globigeriua" -ooze, and is widely distributed 

 over the bed of both the Atlantic and the Pacific. Another 

 deposit is called " Red Clay," and is found at depths exceeding 

 2000 iathoins. Mr. Murray, one of the Challenger naturalists, 

 has carefully worked out the deep-sea deposits which were 

 observed and collected during the expedition. According to 

 him the Glol'tgeruta-ooze occurred in the North Atlantic at forty- 

 nine stations, from depths between 780 and 2675 fathoms ; in 

 the South Atlantic at six stations, from depths of between 1375 

 and 2150 fathoms; and in the Pacific Ocean at twenty-two 

 stations, from depths of between 275 and 2925 fathoms. He 

 also mentions other deposits, viz. Coral-mud, Radiolarian ooze, 

 and Diatomaceous ooze. Mr. Murray also says that volcanic 

 products, such as pnmice, lava, and scari.-e, as well as the 

 peroxide of manganese, are universally spread over the bottom 

 of the dee ) sea; and, in consequence of copper, cobalt, and 

 nickel having been detected in the clays, he was tempted to 

 suggest the presence of meteoric or cosmic dust in those 

 deposits. 



An animated, but quite amicable, controversy has of late years 

 taken place as to whether Globigeriim (from w-hich the first- 

 mentioned ooze has taken its name) lives only on the bottom or 

 on the surface of the sea, or on both of them. You will doubt- 

 less ask, What is a Globigerina ? It is a microscopic shell, 

 consisting of a few globular cells, which are added together in 

 the course of growth, the smallest cell being the original one or 

 nucleus, and the largest being the last formed. All the cells are 

 full of a protoplasmic substance called sarcode, which is 

 amorphous or has no definite structnre — no head, no limbs, no 

 heart, viscera, muscles, or nerves. Its entire body is a stomach, 

 and nothing but a stomach. The same kind of sarcode forms 

 the living palp of sponges, which have a horny or glass-like 

 skeleton instead of a shell. The Globigerina is a member of an 

 extensive and extremely variable class of invertebrate animals 

 called Foraminifera ; and this class, as well as sponges, belong 

 to a kingdom called Protozoa, the name of which imports not 

 that it was the earliest form of life, but that its organisation is of 

 the very primary or simplest kind. The cells of the Globigerina 

 are in their living state covered with the most delicate spines of 

 comparatively great length, which are set outwards, and probably 

 serve to keep at a respectful distance all predatory animals of an 

 equally minute size. Bet»een these spines some of the sarcode 

 is occasionally, if not habitually, protruded at the will of the 

 animal through very fine pores of the shell, which gave rise to 

 the name Foraminifera. Such prolongations or expansions of 



the sarcode are called pseudopodia, and are used for capturing 

 and taking into the body or stomach animal or vegetable particles 

 which serve for food, and are engulfed in the internal sarcode. 

 Having premised thus much, and in the hope that my descrip- 

 tion may be tolerably intelligible to those who have not, like 

 myself, studied the Foraminifera, I will proceed with my account 

 of the controversy. I have frequently taken w ith a towing- net 

 on the surface of the sea a multitude of floating Globigerina, 

 which were certainly alive and showed their pseudopodia as well 

 as their long and thick-set spines. Major Owen and Lieut. 

 Palmer, who especially studied the surface-fauna of the Atlantic, 

 observed and have published the same facts.^ Therefore when, 

 in the joint report of my colleagues and myself to the Royal 

 Society, on the results of the first Porcupine Expedition in 1869, 

 it was stated or strongly inferred that the Globigerina really 

 " inhabit the bottom on which they are found in such extraor- 

 dinary abundance," and that the hypothesis accounting for such 

 accumulation by their having fallen to the bottom after death, 

 their lives having been passed at or near the surface, was con- 

 clusively disproved, I ventured to record my dissent from that 

 conclusion. The observations of i\Ir. Murray, one of the 

 naturalists in the Challenger Expedition, have fully confirmed the 

 hypothesis that Globigerina lives on the surface ; and Sir WyviUe 

 Thomson now admits - it as an established fact. But Dr. 

 Carpenter is not satisfied. He is of opinion that "whilst 

 the Globigerina: are pelagic in an earlier stage of their lives, 

 frequenting the upper stratum of the ocean, they sink to the 

 bottom whilst still living, in consequence of tlie increasing thick- 

 ness of their calcareous shells, and not only continue to live on 

 the sea-bed, but probably multiply tliere — perhaps tliere exclu- 

 sively." 3 I must say that I am not convinced by the instances 

 and arguments which he adduced in support of his opinion. 

 There is no question that a great many species of Foraminifera 

 live always on the sea-bottom ; but I do not know that any 

 species of pelagic or surface-dwelling animal inhabits also the 

 sea-bottom. Dr. Wallich found that the stomachs of star-fislies 

 which came up with the sounding-line from 1260 fathoms con- 

 tained fresh-looking Globigeriniv, and that the latter were full of 

 sarcode. This does not prove much, because sea-water is to 

 some ex'.ent antiseptic or retards putrefaction. Many star-fishes 

 feed like earthworms, and swallow quantities of organic and 

 inorganic matter for the purpose of extracting nutriment from 

 it. Sir Wyville Thomson says, in his paper "On Dredgings 

 and Deep-Sea Soundings in the South Atlantic " (Proc. R. S. 

 vol. xxii. p. 427), that the appearance of Globigerina and certain 

 other Foraminifera, "when living on the surface, is so totally 

 different from that of the shells at the bottom that it is impossible 

 to doubt that the latter, even although they frequently contain 

 organic matter, are all dead." Mr. Murray adds (Proc. R. S. 

 vol. xxvi. p. 535) : — "No living specimen of a Globigerina, an 

 Orbuhna, a Pulvinulina, or of the new genera found on the 

 surface, which undoubtedly came from the bottom, has yet been 

 met with. The foregoing observations appear to justify the 

 opinion that these organisms live only in the surface and sub- 

 surface waters of the ocean. " 



I will not however presume to assert that Dr. Carpenter may 

 not be right ; but is he justified in taking for granted " that the 

 onus probatidi rests on those who maintain that the Globigerina: 

 do not live on the bottom " ? It is rather difficult to prove such 

 a negative. 



The colour of the " Red Clay " was attributed by Mr. Murray 

 to the presence of oxide of iron. 



Mr, Etheridge obligingly examined some of the pebbles and 

 minerals which I had dredged in the Valorous Expedition at 

 depths of from 690 to 1750 fathoms. He reported that many 

 of them were " most likely derived from Iceland." If this were 

 the case, the pebbles and minerals might have been transported 

 by a deep submarine current. 



The deposits in very deep water, and beyond the range of 

 fluviatile and tidal action, are so slight as to be almost filmy, and 

 are chiefly composed of the skeletons or hard parts of Globige- 

 rina, Diatoms, and Radiolaria. The subjacent layer of mud or 

 ooze, where it is beyond the scope of river action, may have 

 been formed from the ruins of a sunken continent. 



The proportion of carbonate of lime contained in the deep- 

 sea mud or ooze of the North Atlantic, which was procured in 

 the first two cruises of the Porcupine Expedition of 1869, slightly 

 differed. In a sample from 1443 fathoms, dredged off the west 



Journal Qi^'t Linnean Society, vol. i 

 Proc. Roy. Soc. vol. .xxiii. p 34. 



1 Ibid. p. 235. 



