;24 



NA rURE 



ypcb. 



who has visited Kulja, gave an interesting account of his expe- 

 riences in that region a few years bacl<. 



Fears had been entertained by many that the expedition sent 

 out by the Russian merchant M. Alexander Sibirialiofir to discover 

 the North Passage by means of the steamer Oscar Dickson, on 

 board of which M. Sibiriakoffwas himself, had been lost, and M. 

 Konstantin Sibiriakoff, his brother, had already equipped another 

 expedition to find and assist the Oscar Dickson. In the mean- 

 time the welcome new; has arrived that Alexander Sibiriakoff 

 reached Tobolsk at the end of December. The Oscar Dickson and 

 another ship, the Nordland, had met fresh ice near Mate-Ssale, 

 and had retired into the Gydan Bay on the coast of Siberia, in 

 order to winter there. 



M. Tarry, a member of the French Commission for Trans- 

 Saharan Communications, is stated to have discovered in the 

 south of Wargla the ruins of a large city called Cedrada, which 

 had been entombed by sands of the desert. This city is placed 

 in the Valley of Wed Mya, and in the vicinity of a number of 

 sources which in former centuries watered thousands of palm- 

 trees. Orders have been sent to procure a set of sounding 

 apparatus, and it is expected a large quaniity of pure water will 

 be extracted from the earth. M. Tarry published an appeal to 

 the local papers in order to obtain from the Government the 

 foundation of a colony in this remote region. 



DEEP-SEA EXPLORATION^ 

 II. 

 4. pOOD. — The late Prof. Sars, in his remarks on the distribu- 

 tion of animals in the depths of the sea, asks " Whence 

 do animals that live at depths far below the limits of vegetation 

 obtain their food ? " Bronn, Wallich, Wyville Thomson, and 

 others have endeavoured to answer this question ; but I do not 

 think the problem has yet been satisfactorily solved. A con- 

 siderable quantity of vegetable food is undoubtedly supplied 

 from the Sargasso Sea and a similar area in the Pacific Ocean, 

 as well as by the sea-weeds w hich fringe every coast. But this 

 supply is not sufficient for the indirect support of the countless 

 host of animals that inhabit the depths of the ocean, all of 

 which are necessarily zoophagous or subsist on other animals, 

 riant life, except perhaps one of a peculiar kind, which will be 

 presently noticed, appears to be absent in depths exceeding 150 

 fathoms. 



In all probability the chief supply of vegetable food is de- 

 rived from the countless diatoms, coccoliths, rhabdoliths, and 

 oscillatorije, which are plants of a low degree of organisation, 

 and swarm on the surface of the sea ; these are swallowed by 

 pelagic animals (such as Salpx and Pteropods, or " sea-butter- 

 flies "), and the latter fall to the bottom after death, and form 

 that flocculent or glairy mass which I have described in the 

 Report of the Porcupine Expedition of 1869 as covering the 

 bed of the North Atlantic at great depths." The preservative 

 effect of sea w.iter on animal tissues would stay decomposition 

 for a long while ; and Mr. Mo=eley ascertained by a curious 

 experiment that it would take only abDut four days for a Salpa 

 to reach the bottom at a depth of 20DO fathoms, and that the 

 Salpa was not greatly decomposed after having remained in 

 sea-water for a month in the tropics. 



When we say that vegetable life does not exist at any con- 

 siderable depth, we must not forget that some kind is said to 

 occur in great abundance even in the benthal or deepest zone. 

 The word "benthal" is applied to depths exceeding 1000 

 fathoms (see my Address, which is referred to hereafter in this 

 lecture). Shells, corals, and other organisms, are everywhere 

 permeated by what are considered to be minute plants allied to 

 fungi or coufervae, which form branching canals, like those of 

 the Cliona or perforating sponge ; and such canals have been 

 also detected in all fo^siliferous strata of a marine nature, from 

 the Silurian to the present epoch. These plants, or Thallophytes, 

 have been called " parasitic" ; but they do not live on any other 

 living thing. They can hardly serve as food for deep-sea animals, 

 because they are never exposed. Whether they may not be a 

 link to connect the animal and vegetable kingdoms may be a 

 matter for further investigation. 



Food is of course a very important factor as regards the size of 

 all animals. I have noticed, in my v.'ork on "British Conchology," 



' A Lecture by J. Gwyn Jeffreys, LL.D., F.R.S. Given at Swansea, 

 Llanelly, and Barrow-in-Furness, in December 1S80 and January i83i. 

 Continued from p. 302. 



" See Proc. Roy. Soc. 1S70, p. 420. 



that Mollusca from moderate depths are generally larger than 

 those of the same species from shallow water ; but this does not 

 seem to be the case with a species of coral obtained in the 

 Challenger Expedition, which ranged from a depth of 30 to one 

 of 2900 fathoms, and was very variable in size. 



5. Light.— W\\toxi tells us of the 



'■ world of waters dark and deep." 

 One of the most interesting problems relating to the subject of 

 this lecture is whether the above is a poetical idea or based 

 on fact, as regards the absence of light in the abysses of the 

 ocean. 



We do not know to what extent the sun's rays penetrate the 

 sea, nor whether the bottom at all depths is absolutely devoid of 

 light. An ingenious apparatus, which was contrived by Dr. 

 Siemens for ascertaining the presence of light at difterent depths 

 by means of highly sensitive photographic paper, has never yet 

 been properly tried. An experiment of this kind made by Prof. 

 Forel proved that in the Lake of Geneva, even at a depth of 

 only thirty fathoms, the paper was entirely unaffected after pro- 

 tracted exposure. But the water of that lake is peculiar ; it is 

 said to be rendei-ed less transparent by suspended and floating 

 particles of mica brought from glacier streams, and to have thus 

 acquired its deep blue colour. I cannot believe that the only 

 abyssal light, if there be any, is phosphorescent. 



At all events we are certain that, as regards the sea, many 

 animals at very great depths have eyes, and that there is no 

 absence of colour. 



Cuttlefishes, which have eyes not less highly organised than 

 our own, have frequently been obtained from depths of many 

 Iiundred fathoms ; they do not eat phosphorescent polypes and 

 such small deer. Nor are the deep-sea Mollusca blind. During 

 the Porcupin-; Expedition of 1869 an undescrlbed species of 

 Pieurotroma from 2090 fathoms had a pair of well-developed eyes 

 on short footstalks; and a Fusus from 1207 fathoms had its eyes 

 at the base of the tentacles. The last-named mollusks chiefly 

 prey on bivalves. I have taken at moderate depths, living on 

 the same ground, closely-allied species 'of univalve mollusks, 

 some of which were eyeless or blind, and others were provided 

 with the usual organs of vision. Numerous instances have been 

 given by the Challenger naturalists of apparently seeing as well 

 as of apparently sightless animals taken at great depths. Prof. 

 Semper, of Wurzburg, says, in " The; Natural Conditions of 

 Existence as they Affect Animal Life " (1881), "Many creatures 

 furnished with well-constructed eyes live associated with the 

 actually blind species, and which have been partly enumerated 

 above." He mentions among the former five species of fish (one 

 of a new genus) discovered in the Challenger Expedition-at 

 depths of from 675 to 2040 fathoms, besides several Mollusca 

 and Crustacea. 



Some land-slugs and mollusks (e.g. Geomalacus maculosus and 

 Achatina aciaila) are also blind. On the sea-shore and in 

 shallow water most bivalves, as well as all the species of Chiton, 

 are eyeless. 



Some deep-sea animals are brightly and deeply-coloured. In 

 the Challenger Expedition shrimps "of an intense bright scarlet 

 colour " were obtained in very great abundance ; and many 

 Molothurians or Sea-cucumbers were of a "deep purple" hue. 

 The same observation occurred to me in the Porcupine and 

 Travailleur Expeditions. 



6. Temperature. — The highest temperature of the sea-bottom 

 observed in the Challenger voys.%t at depths over 1000 fathoms 

 was 5o°'5 Fahr., in 2550 fathoms ; the lowest was 32"' i only, in 

 1950 fathoms. The average bottom-temperature at great depths 

 does not much exceed the freezing-point ; but life does not 

 appear 10 be affected by that circumstance. In the Arctic 

 Expedition of 1875 I found an abundance and variety of animals 

 in icy cold water. 



7. Depth. — The average depth of the ocean between latitudes 

 60" N. and 60° S. is nearly three miles, or 2500 fathoms. The 

 greatest depth which has been ascertained by sounding is five 

 miles and a quarter, or 4620 fathoms, and occurs in the North- 

 west Pacific Ocean ; it is nearly equal to the height of Mount 

 Everest, the highest known mountain, in the proportion of 

 27,720 to 29,000 feet. 



8. Inequalities of the Sea-bottom. — The operations of the 

 Telegraph Construction and Maintenance Company have mate- 

 rially added to our knowledge of the shape and contour of the 

 floor of the ocean. They have shown us that the bed of the sea 

 is quite as uneven as the surface of the land, and that it repre- 

 sents the same mountains, hills, gorges, and valleys, equally 



