Feb. 8, 1877] 



NATURE 



3'9 



as a separate branch, diverging from the common stem of 

 the genus Gentiana, even before G. lutea. For whilst 

 in all other species of Gentiana the honey is secreted by 

 an annular swelling of the base of the pistil, in this group 

 the nectaries are situated at the base of the corolla itself, 

 between the filaments {n, Figs. loi, 105). As hitherto 

 G. tenella and G. nana have been distinguished only by 

 somewhat fluctuating characteristics, it may be of especial 

 interest that in G. tenella I have found each interstice 

 between two filaments to contain two nectaries («, 

 Fig. loi), in G. nana only a single one («, Fig. 105). 



To the same group belong G. campestris, germam'ca, 

 amarella, and obtitsifolia, two of which have been directly 

 observed by myself to be visited both by Lepidoptera and 

 butterflies. For instance, near Pontresina and in the 

 Val del Fain, August 6-8, 1876, I saw G. campestris re- 

 peatedly visited by Bombtcs mendax, Gerst. '%, but also 

 by butterflies {Argynnis pales, Hesperia serratulcs, Co lias 

 phicomone, Lyccena argus). 



The fourth group of Alpine species of Gentiana exclu- 

 sively adapted to cross-fertilisation by Lepidoptera, will 

 be treated of in my next article. 



Lippstadt Hermann Muller 



(TV? be continued.^ 



DEEP SEA MUDS^ 



T~\URING the present session I propose to lay before the 

 Society several papers on subjects connected with the 

 deposits which were found at the bottom of the oceans and seas 

 visited by II.M.S. Challenger in the years 1872, 1873, 1874, 

 1875, and 1876. 



Instruments in use for obtaining information of the deposits. 



It will be convenient to introduce this first communication 

 with a brief description of the instruments and methods employed 

 on board H.M.S. Challenger with the view of obtaining informa- 

 tion and specimens of these ocean deposits. The instrument in 

 most frequent use was the tube or cylinder forming part of the 

 sounding apparatus. 



During the first six months of the cruise this cylinder was one 

 ka\ing less than an inch bore, and was so arranged with respect 

 to the weights or sinkers that it projected about six inches 

 beneath them. The lower end of the cylinder was fitted with a 

 common butterfly valve. This arrangement gave us a very small 

 sample of the bottom. 



In July, 1873, this small cylinder was replaced by one having 

 a two- inch bore, and it was also made to project fully eighteen 

 inches below the weights. This was a great improvement, as 

 it gave a much great< r quantity of the bottom in most soundings. 



The tube was, in the clays, frequently forced nearly two ftet 

 into the bottom. On its return to the ship, the butterfly valves 

 were removed, and a roll of the clay or mud, sometimes eighteen 

 inches in length, could be forced from it. In this way we Itarned 

 that the deeper layers were very frequently different from those 

 occupying the surface. 



In the organic oozes — as the Globigerina, Pteropod, Radio- 

 larian, and Diatom oozes — the tube did not usually penetrate 

 the bottom over six or seven inches, these deposits offering more 

 resistance than the clays and muds. Occasionally the tube came 

 up without anything in it, but the outside was marked with 

 streaks of the black oxide of manganese. In about thirteen out 

 of nearly four hundred soundinf;s we did not get any information 

 of a reliab'e nature about the deposit. 



The dredge in use was a heavy modification of Bali's natu- 

 ralist's dredge, and the trawl was the ordinary beam trawl of the 

 fishermen. 



Both of these instruments had generally a bag of canvas or 

 other coarse cloth sewed into the boitom of the netting, to pre- 

 vent the soft clay or ooze from being entirely washed out. In 

 this way we, at many station?, got, along with animals, a large 

 quantity of ooze, clay, stones, or manganese nodules. 



While trawling or dredging the ship often shifted her position 

 a mile or two, but we could not tell whether the dredge or trawl 



' " On the Distribution of Volcanic Debris over tlie Floor of the Ocean ; 

 its Character, Source, and some of the Products of its Disintegration and 

 Decomposition," by Mr. John Murray. Read at the Royal Society, Edin- 

 burgh. 



had been working over all that distance, or had merely taken a 

 dip into the deposits. This should be remembered when com- 

 paring the captures in one locality with those of another. 



Altogether there is much uncertainty about the behaviour of 

 the trawl and dredge in deep water. It occasionally happened 

 that when the greatest care was taken, and when it was believed 

 that the trawl had been dragging for some hours, it came up 

 without anything in it, or any evidence upon it or in the attached 

 tow-nets to show that it had been on the bottom. 



During the last year of the cruise a tow-net was attached to 

 the dredging line just below the weights, which last were placed 

 a few hundred fathoms in front of the trawl or dredge. Tow- 

 ntts were also attached to the trawl and dredge. These nets 

 frequently came up nearly full of mud, and almost always con- 

 tained minute things and fragments from the surface layers of the 

 bottom. 



At times the water-boltle attached to the sounding line came 

 up with clay or ooze in it, or had some of the deposit adherinjj 

 to its under-surface. 



These then were the means and methods employed for getting 

 information concerning ocean deposits, and collectively they 

 have furnished us with a large amount of material. A careful 

 examination of the specimens procured has already much in- 

 creased our knowledge of th e nature and distribution of ocean 

 deposits, of the sources of the materials of which they are built 

 up, and of the chemical processes taking place in the deep waters 

 and on the floor of the ocean. 



The Volcanic debris in Ocean Deposits and sonie of the Prcducts 

 of its Disintegration and Decomposition. 



In a preliminary report to Prof. Wyville Thomson, which 

 has been published in the Proceedings of the Royal Society of 

 London, I pointed out the wide-spread distribution of volcanic 

 dibris in ocean deposits, and its probable influence in the forma- 

 tion of deep sea clays, and manganese nodules or depositions. 

 In this paper I propose to treat of these subjects in more detail, 

 and to give some of the results of observations which have been 

 made since the above report was written. 



Pumice-Stones. 



The form of volcanic debris most frequently met with in ocean 

 deposits is pumice stone. 



Specimens of these stones, varying from the size of a pea to 

 that of a foot-ball, have been taken in dredging at eighty of our 

 stations. I have placed the position of these stations on a map, 

 from which it will be seen that they occur all along our route. 



Near volcanic centres the dredge has frequently brought them 

 up in great numbers, as off the Azores in the Atlantic, off New 

 Zealand and the Kermadec Islands, at several places among the 

 Philippine Islands, off the coast of Japan, and. elsewhere. As a 

 rule, they are not numerous in shore deposits when these are 

 distant from volcanic regions. In deposits far from land they 

 are most abundant in deep sea clays, from vehich the shells and 

 skeletons of surface organisms have been all or nearly all 

 removed. 



In the North Pacific the trawl brought up bushels of them 

 from depths of 2,300 and 2,900 fathoms. Perhaps in no single 

 instance have we trawled successfully on any of our deep sea 

 clays without getting numbers of these stones. If there be an 

 exception it is in the North Atlantic. But here it is to be re- 

 membered that while we were investigating the conditions of the 

 North Atlantic, our attention had not yet been directed to the 

 importance of detecting the presence of pumice, and we have 

 not preserved such large samples of the North Atlantic deposits 

 as those of other regions. 



On the whole, pumice-stones are more numerous in the Pacific 

 than in the Atlantic deposits. 



In the Globigerina and other organic oozes, they are abundant 

 or otherwise, according as the deposit is near or far removed 

 from volcanoes. In these oozes they never occur so abundantly 

 as in the clays. They are more or less masked and covered up 

 by the accumulated remains of foraminifera, diatoms, or other 

 surface organisnos. In like manner they are obscured in shore 

 deposits by river and coast detritus. Besides those specimens, 

 which are sufficiently large to be examined by the hand, we 

 detected with the microscope minute particles of feldspar in all 

 our ocean deposits. 



An inspection of the specimens which I have placed on the 

 table will show that the majority of these pumice stones have a 

 rolled appearance. Some of them have undergone much decom- 



