94 



NATURE 



{June I, 1876 



was something quite novel to the explorers. At the mean 

 maximum depth of some 2,200 fathoms the ooze was one 

 vast mass of the calcareous shells of foraminifera, but as 

 the soundings got deeper the ooze began to assume a 

 darker tint, and showed, on analysis, a continually de- 

 creasing quantity of calcareous matter. Now in this red 

 ooze almost no calcareous forms were to be met with, and 

 it was of extreme fineness, remaining for a long time in 

 suspension in water, and proving on analysis to be almost 

 pure clay, a silicate of alumina and the sesquioxide of 



Fig. I. — Eiiplectella suberea. 



iron, with a small quantity of manganese ; and at this 

 depth there appeared to be an absence of animal life. 



Prof. Wyville Thomson considers it as quite proved that 

 all the materials for such deposits, with the exception of the 

 remains of those animals which are now known to live at 

 the bottom at almost all depths, are derived from the 

 surface ; and considering the very enormous extension of 

 the calcareous ooze, it becomes important to know 

 something of the minute foraminifera that produce it. 

 In all seas, from the equator almost to the polar ice, the 

 surface-water contains Globigerincp. They are more abun- 



dant and of a larger siz2 in warm seas ; several varieties 

 attaining a large size, and presenting marked varietal 

 characters, are found in the intertropical area of the 

 Atlantic. In the latitude of Kerguelen they are less 

 numerous and smaller, while further south they are still 

 more dwarfed, and only one variety, the typical Globi- 

 geiina biilloidcs, is represented. The living Globigerince 

 from the tow-net are singularly different in appearance 

 from the dead shells we find at the bottom (Fig. 2). The 

 shell is clear and transparent, and each of the pores 

 which penetrate it is surrounded by a raised crest, the 

 crest round adjacent pores coalescing into a roughly 

 hexagonal network, so that the pore appears to lie at the 

 bottom of a hexagonal pit. At each angle of this hex- 

 agon the crest gives off a delicate flexible calcareous 

 spine, which is sometimes four or five times the diameter 

 of the shell in length. The spines radiate symmetrically 

 from the direction of the centre of each chamber of the 

 cell, and the sheaves of long transparent needles, cross- 

 ing one another in different directions, have a very beau- 

 tiful effect. The smaller inner chambers of the shell are 

 entirely filled with an orange-yellow granular sarcode ; 

 and the large terminal chamber usually contains only a 

 small irregular mass, or two or three small masses run 

 together, of the same yellow sarcode stuck against one 

 side, the remainder of the chamber being empty. No 

 definite arrangement, and no approach to structure, was 

 observed in the sarcode ; and no differentiation, with 

 the exception of bright-yellow oil-globules, very much 

 like those found in some of the Radiolarians, which are 

 scattered apparently irregularly in the sarcode, and 

 usually one very definite patch of a clearer appearance 

 than the general mass coloured vividly with a carmine 

 solution. The presence of scattered particles of bioplasm 

 was indicated by minute spots here and there throughout 

 the whole substance which received the dye. 



When the living Globigerina is examined under very 

 favourable circumstances, that is to say, when it can be 

 at once placed under a tolerably high power of the 

 microscope in fresh still sea-water, the sarcodic contents 

 of the chambers may be seen to exude gradually through 

 the pores of the shell, and spread out until they form a kind 

 of flocculent fringe round the shell, filling up the spaces 

 among the roots of the spines and rising up a little way 

 along their length. This external coating of sarcode is 

 rendered very visible by the oil-globules, which are oval, 

 and filled with intensely-coloured secondary globules, and 

 are drawn along by the sarcode, and may be seen, with a 

 little care, following its spreading or contracting move- 

 ments. At the same time an infinitely delicate sheath of 

 sarcode containing minute transparent granules, but no 

 oil granules, rises on each of the spines to its extremity, 

 and may be seen creeping up one side and down the 

 other of the spine with the peculiarj^tiwz;;!^ movement with 

 which we are so familiar in the pseudopodia of Gromia 

 and of the Radiolarians. If the cell in which the Globi- 

 geritia is floating receive a sudden shock, or if a drop ot 

 some irritating fluid be added to the water, the whole 

 mass of sarcode retreats into the shell with great rapidity, 

 drawing the oil-globules along with it, and the outhne of 

 the surface of the shell and of the hair-like spines is left 

 as sharp as before the exodus of the sarcode. 



There is still a good deal of obscurity about the nature 

 of Orbulina universa, an organism which occurs in some 

 places in large proportion in the globigerina ooze. The 

 shell of Oi'bidina (Fig. 3) is spherical, usually about "5 mm. 

 in diameter, but it is found of all smaller sizes. The 

 texture of the mature shell resembles closely that of Globi- 

 gerina, but it differs in some important particulars. The 

 pores are markedly of two different sizes, the larger about 

 four times the area of the smaller. The larger pores are 

 the less numerous ; they are scattered over the surface 

 of the shell without any appearance of regularity ; the 

 smaller pores occupy the spaces between the larger. The 



