TIIANSACTIONS OK SECTION I). 



r49 



rccodfil from. Unforliiiiatfly mv knowledpo of pdiifric vo^retablo lifo i,i vti-y ini- 

 wift'Ct, iiiiil it i-^ to l)t' Iioiieil that Ijotuiii.^t.s luiiy In' k-il to liikis up tlm Milijt>r"l ami 

 .iriii" td^rt'tliur wliftt is Ituowii witli n'^runl to tin* ^rcolnyiciil raiinvM mid iilMimlaiin) 

 of tilt' various liir^rcr sfuwct'ds, tricliodt'smiuni, diiitom.x, and otliitr al;rif hv wliicli 

 tlie sea-f^iirfaci' ia iidiiihiti'd. It will, then, !»* iio.s.tiliii' to I'oriu a iifarcr t'siiiiiatn 

 of til t'Ntoni to wliif'h tht'sc ]>huils aif caiiahlo of form in;.' a .sutlicifiit ultiinali! 

 |iii)d-)"Mn'Pt' for tilt' iiicatcr part of the ]ielaf.'ic fauna, and tlirouyh it of deep-sea 

 life. The question is of inii)oitance, because it' tiio d^ep .sea, having' noulliniatt) 

 source f)f food in itself, derived its nuiin .sunply from tho coasts ami land-surfaces 

 ill tlu^ early liistory of the hahilation nf the ^'lohe l)y animals, tln-re ran liavn 

 rvidti'd snireely any deep-sea I'aniia until the littoral and tcrrrstrial rauiias and 

 ibnis had becoiu" well e.stahlished. 



Wlii'llier the littoral and terrestrial plants or the jielajrie \m proved to havt> 

 tlip lavpT i*liare in composinj; the ultiniat(« fooil-.soiiree of the deep t^ea, it .seems 

 nTtain that the inod iis it reaches tlie dee]) sea is mostly in the form of dead 

 matter, and 1 iinafriue that tlie Ion;: but sleudiT liaekwardly tlirected teeth of many 

 (iei'p-.-i'a tish, re.sembliiiij: those of snakes, are ii>ed rather as aids fur swallowiii;.' 

 wliiile other li.slies which have faUeii from abovi^ dead, and thus tuakiiifj: the best I'f 

 an occasional opportunity of a meal, than for catchin;,' and killinjr livin^r prey. In. 

 a lecture on 'Lite in the Deep tSea,' delivereil in 1880,' I suj:^'e.sted that putrefac- 

 tion of ori.'anic matter, such as ordinarily occurs tdsewhere, may possibly l)e entin ly 

 aWiit ill the dee]) sea, tho bnctcrla ami other microphytes which cause it beiti;.;' 

 jins,-<ibly ab.s'nt. Some interostiii<r experiments with re_'ard to this f|Uc.stion have 

 lately lieen made by M. A. Certes.- lie added to sterili.-ied .■solutions of liay- 

 I'.xtract, milk, broth, and other nrfranic nutrient fluids mixed with ,-ea-water, with 

 the usual nece.-*sarv precautions, small quantities of de(^p-sea mud, or deep-se,i 

 water, procured by the ''rravailleur' and 'Talisman.' In .some experiments air wa.s 

 present; others were madt; in vacuo. In nearly all the former ]mtrefact ion occurred 

 after some time, espec'ally after application of warmth, and micro-orj,'anisms were 

 developed, whilst the latter remained without exception tterile, apparently iiuli- 

 catiii;,' that the microbes which live wliere air is absent are not present in the deep 

 jua. The others whicli developed in the presence of oxyfjfen n.r.y possibly have 

 .xiinkfroin the surface to the bottom, and have retained their vitality, although it 

 iaiiot improbable that they may be incapable of active existence and multiplication 

 under tho phy.4cal condition.s tliere existing. M. Certes is to make further 

 cKpeviraents on this question under conditions of ])re.ssure and temjieratiire a.s 

 nearly re.senibliiif;' those of the deep sea as possible. In the deeji sea the ordinary 

 cycle of chemical cbanjjes of matter produced by life is incomplete, there being no 

 plants to work up the decomposition products. Tbe.se, therefore, in the absence of 

 any rapid chaniro of the deep-sea water.s, must accumulate there, and can only be 

 turned to account when they reach the surface-waters on the littoral refrions. 



Alniiy interesting results may be expected to be obtained when the histology of 

 animals from great depths comes to be worlvcd out, and especially that of the 

 special .sense-organs. At present very little has^ been attempted in this direction, 

 principally, no doubt, because deep-sea specimens are too precious to be used for 

 the purpose. In a remarkable scopelid fish dredged by the ' Challenger ' from deep 

 ■water, Ipnopt Murrcnji oi Dr. Giinther, the eyes are curiou.sly flattened out and 

 occupy the whole upper surface of the mouth. They are devoid of any trace of 

 k'ns or iris, and, as appears from ol).servations by ^Ir. John Murray and my own 

 examination of his preparations, the retina consists of a layer of long rods, with a 

 very thin layer indeed of nerve-fibres in front of it, and apparently no intervening 

 L'lanular ganglionic or other laj'ers. The rods are disposed in hexagonal bundles, 

 the free ends of which rest on corresponding well-defined hexagonal areas, into 

 which the choroid is divided. It is probable that aberrant structures may be found 



' Ticcture delivered at the Royal Institution, March 5, 1880, Nature, April 22, 



p. rm. 



' ' Siir la Culture, i\ Tabri dcs Gcrmos Atmospheri(iues, des Eaux et des Sediments 

 rapportes par les Expeditions du " Travailleur " et du "Talisman," 1883, 1883,' 

 (Amptcs-Rcndus, No. 11, 11 mars 1884, p. 690. 



' 



