494 



NATURE 



{Sept. 28, 1876 



agree with him. The tow-net upon the surface, and particularly 

 at a little below the surface — that is to say, to the depth of a few 

 fathoms, or even to a hundred fathoms — takes enormous numbers 

 of these Foraminijera, which make up the Globigerina ooze alive. 

 The Globi^erince themselves, in many seas, are most abundant, 

 and they present characteristics totally different from the shells as 

 we find them below ; so that I think there cannot be the slightest 

 doubt that these shells live on the surface, and a little below the 

 surface, and that the whole material at the bottom composed of 

 these shells is derived from the surface. When we find these 

 shells at the bottom they are little globules all united together, 

 and forming a little compound mass of globules. These are 

 rough on the surface, and perforated with minute pores. The 

 cavity of the shell contains a little reddish material, which, at 

 first, we were inclined to suppose was the remains of the body 

 of the animal. When the Globigerina was found on the surface, 

 the shell was of the same form, but instead of being white and 

 opaque, it was perfectly clear and transparent. A raised frill on the 

 shell forms a hexagon round each minute pore and runs into six 

 points, and from each point a long spine projects — in fact the 

 shell bristles with long spines running out in every direction, the 

 axes of the spines on each chamber meeting in the centre of the 

 chamber. The shell has a little animal in the interior of it, and 

 that animal consists of a particle of gelatinous matter like the 

 white of egg, and when alive this matter runs out of the holes on 

 the surface of the shell to the end of each of the spines, where it 

 absorbs minute particles of organic matter floating in the water. 

 The Globi^erincE seem to be of the same specific gravity as the 

 water, their weight being reduced by large oil-globules scattered 

 in quantity through their substance ; they exist in myriads on the 

 surface, while they are perpetually dying and sinking to the 

 bottom. Finding them so abundant in a living condition on the 

 surlace or a little below, and finding none living at the bottom, 

 there seems to be little room for doubt that the Globigerina ooze 

 is due simply to the accumulation of the dead shells of the inha- 

 bitants of the surface and of moderate depths. We should there- 

 fore at once come to the conclusion, if this be true, that the forma- 

 tion which arises from their accumulation ought to be as universal 

 as they are themselves. Singularly enough, this is not the case, 

 and this is one of the most curious points which we have deter- 

 mined. When we go to a depth of about 2,000 fathoms we find 

 that the shells at the bottom are becoming, as it were, rotten or 

 yellow, they have not the same white clear appearance which 

 they had in shallower water, and if we go to a depth of 2,500 

 fathoms or so, we find no shells whatever, but that the bottom 

 consists of a homogeneous red mud, which, instead of consisting 

 of carbonate of lime, is formed of the materials of ordinary clay. 

 Now, as a very large portion of the sea is below 2,000 fathoms 

 in depth, probably by far the greatest portion is being now 

 covered by red clay, and not by calcareous formations. The 

 question at once arises, How is it possible that these calcareous 

 formations are stopped at a certain point and replaced by red 

 clay ? There is no doubt that the calcareous formation is arrested 

 by the carbonate of lime being in some way or other removed 

 from the shells of these creatures. When we come to a certain 

 depth the carbonate of lime is dissolved, and we have a fine red 

 clay instead. The cause of the removal of the carbonate of lime is 

 as yet rather obscure. We were at first inclined to believe that it 

 is removed by excess of carbonic acid in the water. If the water 

 contained an excess of this acid it would dissolve these shells, 

 and it is just possible that the excess of carbonic acid in these 

 depths may remove the carbonate of lime. We also find a large 

 quantity of sulphate of lime dissolved in the sea, and it is just 

 conceivable that a considerable amount of sulphurous acid may 

 be percolating through the crust of the earth at various places, 

 and that it may be converted into sulphuric acid, which would 

 dissolve the carbonate of lime. But whatever be the reason 

 there cannot be the slightest doubt that on reaching 2,000 fathoms 

 depth.the lime is gradually removed, and we have the red clay. 

 There is another important and curious question arising — namely, 

 where does the red clay come from ? The red clay consists of 

 the silicate of alumina and iron. This compound does not exist 

 in any quantity in the shells in that particular form, and there is 

 no doubt that some complicated changes taking place in the sea 

 at this moment are producing this silicate of alumina and per- 

 oxide of iron. There is one very remarkable thing which has 

 been observed by Mr. Murray and Mr. Buchanan, who have 

 been watching this matter with great care, and that is that all 

 oyer the sea there is a large quantity of pumice. Volcanoes — 

 either sub-serial or sub-marine— either exposed to the air or under 



the water — are perpetually throwing out material from the crust 

 of the earth, and the pumice, which is the froth of the lava — lava 

 divided minutely and containing bubbles either of steam or air — 

 is very frequently so light as to float freely in water ; and almost 

 wherever we were, in all parts of the world, we found that par- 

 ticles of this pumice had been caught by the sea, and so moved 

 about in currents slowly over the surface of the ocean. In almost 

 all parts of the sea, the trawl or the dredge brought up bits of 

 pumice which had been waterlogged and had fallen down to the 

 bottom, probably after swimming or floating about for a very 

 great length of time. This pumice was constantly in various 

 stages of decomposition, and its decomposition like that of all 

 felspathic minerals must result in the production of a clay. It is 

 very certain now that these calcareous formations which are 

 being produced by the animals floating upon the surface of the 

 sea and falling to the bottom, and there accumulating, are by no 

 means universal, but that besides these there are huge formations 

 of clays which are capable of giving rise to important formations 

 of schists being produced at the bottom of the sea at the present 

 day. Over the whole bottom of the Pacific, or a very large part 

 of it, we find red clay, and particularly in the North Pacific, 

 where there is a great depth of water. The red clay has all 

 through it nodules, which vary from the size of sago or a canary- 

 seed to the size of a child's head or an orange, composed of nearly 

 pure peroxide of manganese. These are found in enormous 

 quantity. The trawl sent down to the bottom in those regions 

 brings up masses of concretions, much resembling lumps of the 

 mineral known as wai, almost all of which contain as a kernel 

 in the interior a fish's tooth, or a little bit of sponge, or some 

 fossil of some kind, which has formed the nucleus round which 

 the manganese has accumulated. This is altogether a most 

 peculiar and novel observation. In the Atlantic and all over the 

 bottom of the sea we find manganese in minute bits, but in the 

 North Pacific particularly these pieces are in very great quantity 

 and attain a large size. This is a phenomenon which we are as 

 yet unable to explain, and I do not know that there is any 

 analogous instance in any of the older formations. 



Along with the Foraminifera we have living in the sea a great 

 number of extremely beautiful little organisms, which are known 

 under the name of Radiolarians. Instead of these having cal- 

 careous shells, they have silicious shells — sometimes external, 

 sometimes internal, but very generally presenting extremely 

 beautiful forms. The Foraminifera appear to live mainly upon 

 the surface, or a little below it. In regard to the Radiolarians, 

 it seems to be somewhat different, for when the tow-net is 

 dragged along the sea even at the depth of 1,000 fathoms, we 

 find that the number ol Radiolarians increases, and that the size 

 of the specimens of the species which are found on the surface is 

 rather greater ; and many forms occur at those great depths 

 which are not found on the surface at all. Therefore we are 

 inclined to believe that the Radiolarians live all through the sea, 

 and down to its greatest depths, which may be something like 

 five miles. Now, you can easily understand that these things, 

 living in this way, add considerably to the formations which are 

 taking place at the bottom. We even found a formation which 

 has been called by Mr. Murray Radiolarian ooze, on account of 

 its consisting almost entirely of the remains of Radiolaria, The 

 mode of formation of this ooze is peculiar ; it seems that the 

 Foraminifera, living only near the surface, have their shells 

 entirely dissolved before they reach the bottom ; the red clay is 

 laid down as usual, whatever may be its source ; but the shells 

 of the Radiolarians, living throughout the whole of the vast 

 depth, are so numerous as entirely to overcome and mask all the 

 other constituents of the bottom. This formation, however, only 

 occurs at very extreme depths^ and it is therefore apparently in 

 patches at the bottom of the sea. In the Southern Sea, where 

 the depth is not so great as the Pacific or Atlantic, we find that 

 the surface, instead of being covered with Radiolarians is covered 

 with a set of minute plants which have silicious coverings. Those 

 plants are living on the surface in enormous quantity, and conse- 

 quently dying on the surface. And when you drag the dredge 

 or trawl over the bottom it comes up with a white matter, which 

 looks at first extremely like chalk, though it is formed entirely 

 of silica. There are many other points of great interest connected 

 with these recent deposits, but my time will not allow me to 

 refer to them. I will, therefore, now pass on to the second ques- 

 tion of special prominence — the climates of the sea. 



The temperature at the depth to which I alluded — namely, 

 2, 500 fathoms — is very low. Over the whole bottom of the Pacific 

 and the Atlantic, and those portions of the Southern Sea which 



