Sea-hottom procured by II.M.S. ' Challenger. 289 



shows that the specimen from which it was taken had both its 

 chambers and the flask-shaped cavities of the exogenous deposit 

 filled with sarcode not tlistiiiguishable in any respect from that of 

 the floating specimens. From these important observations (wliich 

 had not been made public when the sheet of my ' Introduction to 

 the Study of the Foraminifera ' comprising the Globigerine family 

 passed through the press, but which I have myself subsequently 

 confirmed in every particular) it seems an almost inevitable in- 

 ference that the subsidence of the Globu/erinie to the bottom is the 

 consequence, not of their death, but of the increasing thickness 

 and weight of their shells, produced by living action. As long as 

 the number of segments continues to increase, the carbonate of 

 lime separated by the sarcodic body from the circumambient water 

 goes to form the walls of additional chambers ; but when this 

 chamber-formation ceases (which usually occurs when the shell 

 consists of either 12 or 10 segments), it is appUed to thicken 

 the walls of the chambers already formed ; and from the rapid 

 subsidence of the Globujerime taken up from the sea-bottom when 

 thrown into a jar of sea-water, it seems to me inconceivable that 

 they can be floated by their animal inhabitants when once the 

 exogenous deposit has attained any considerable thickness. 



That the Globiyeriiue which have subsided to the bottom con- 

 tinue to Live there, is further indicated by the condition ot" the 

 sarcodic contents of their shells. In any sample of Glubi/jeriaa- 

 ooze that I have seen brought up by the dredge or the sounding- 

 apparatus, part of the shells (presumably those of the surface- 

 layer) were tilled with a sarcode body corresponding in condition 

 with that of Foraminifera known to live on the sea-bed, and 

 retaining the characteristic form of the organism after the re- 

 moval of the shell by dilute acid. As Dr. AV^allich pointed out 

 (' North-Atlantic Sea-bed,' p. 139), the sarcode of these is viscid, 

 and inclined to coalesce again when crushed ; the shell has a vivid 

 but light burnt-sienna colour ; and sarcodic bosses, like retracted 

 pseudopodia, are distinguishable upon its exterior. The only mis- 

 giving 1 ever bad in regard to the living condition of the Globi- 

 (jerince presenting these characters, was caused by the absence of 

 any pseudopodia! extensions ; and this source of doubt has been 

 now removed by the statement of Prof. Wyville Thomson, that 

 no pseudopodia have ever been observed by Mr. Murray to be put 

 forth by the Globijer'uue captured in surface-waters. — In the same 

 sample will be found shells distinguishable from the preceding 

 by their dingy look and greyish colour, by the want of consistence 

 and viscidity in their sarcode contents, and by the absence of any 

 external sarcodic investment ; these are presumably dead. Other 

 shells, again, are entirely empty ; and even when the surface- 

 stratum is formed of perfect Globif/erime, the character of the 

 deposit soon changes as it is traced downwards. " The sedi- 

 ment," as was correctly stated by Prof. Wyville Thomson, " gra- 

 dually becomes more compact ; and a slight grey colour (due, 

 probably, to the decomposing organic matter) becomes more pro- 



