36 THE POPULAR SCIENCE MONTHLY. 



taken as proved that all the materials of such deposits, with tlie exception, of 

 course, of the remains of animals which we now know to live at the hottom of tdl 

 depths, which occur in the deposit as foreign bodies, are derived from the surface. 



"Mr. Murray has combined with a careful examination of the soundings a 

 constant use of the tow-net, usually at the surface, but also at depths of from 10 

 to 100 fathoms, and he finds the closest relation to exist between the surface 

 fauna of any particular locality and the deposit which is taking place at the 

 bottom. In all seas, from the equator to the polar ice, the tow-net contains 

 GlohigeriiKe. They are more abundant and of a larger size in warmer seas; 

 several varieties, attaining a large size, and presenting marked varietal charac- 

 ters, are found in the intertropical area of the Atlantic. In the latitude of Ker- 

 guelen they are less numerous and smaller, while farther south they are still 

 more dwarfed, and only one variety, tlie typical Globigerina lulloidcs, is repre- 

 sented. The living Glohlgerinm from the tow-net are singularly different in 

 appearance from the dead shells we find at the bottom. 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 net- 

 work, so that the pores appear to lie at the bottom of an hexagonal pit. At each 

 angle of this hexagon 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 

 shell, and the sheaves of long ti-ansparent needles crossing one another in differ- 

 ent directions have a very beautiful 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 excep- 

 tion of round bright-yellow oil-globules, very much like those found in some of 

 the radiolarians which are scattered, apparently irregularly, in the sarcode. We 

 never have been able to detect, in any of the large number of Glohigcrinae 

 which we have examined, the least trace of pseud opodia, or any extension, in 

 any form, of the sarcode beyond the shell. . . . 



" In specimens taken with the tow-net the spines are very usually absent ; 

 but that is probably on account of their extreme tenuity ; they are broken oflT 

 by the slightest touch. In fresh examples from the surface, the dots indicating 

 the origin of the lost spines may almost always be made out with a high power. 

 There are never spines on the Glohigerince from the bottom, even in the shallowest 

 water." 



There can now be no doubt, therefore, that the Glohlgerlncc live at 

 the top of the sea; but the question may still be raised whetlier they 

 do not also live at the bottom. In favor of this vieAV, it has been 

 urged that the sliells of the Glohlgerlnce of the surface never possess 

 such thick walls as those which are found at the bottom, but I confess 

 that I doubt the accuracy of this statement. Again, tlie occurrence 

 of minute GlohlgerincB in all stages of development, at the greatest 

 depths, is bi'ought forward as evidence that they live in situ. But, 

 considering the extent to which the surface-organisms are devoured, 

 without discrimination of young and old, by Salj^ce and the like, it is 

 not wonderful that the shells of all ages should be among the rejecta- 



