160 LAY SERMONS, ESSAYS, AND REVIEWS. [ix. 



vast depths from which apparently living Globigerincc have been 

 brought up, does not agree very well with our usual conceptions 

 respecting the conditions of animal life ; and it is not so 

 absolutely impossible as it might at first sight appear to be, that 

 the Globigcrincc of the Atlantic sea-bottom do not live and die 

 where they are found. 



As I have mentioned, the soundings from the great Atlantic 

 plain are almost entirely made up of Gloligerince, with the 

 granules which have been mentioned, and some few other 

 calcareous shells ; but a small percentage of the chalky mud 

 perhaps at most some five per cent, of it is of a different nature, 

 and consists of shells and skeletons composed of silex, or pure 

 flint. These silicious bodies belong partly to the lowly vegetable 

 organisms which are called Diatomacece, and partly to the minute, 

 and extremely simple, animals, termed Radiularia. It is quite 

 certain that these creatures do not live at the bottom of the 

 ocean, but at its surface where they may be obtained in 

 prodigious numbers by the use of a properly constructed net. 

 Hence it follows that these silicious organisms, though they are 

 not heavier than the lightest dust, must have fallen, in some 

 cases, through fifteen thousand feet of water, before they reached 

 their final resting-place on the ocean floor. And, considering 

 how large a surface these bodies expose in proportion to their 

 weight, it is probable that they occupy a great length of time in 

 making their burial journey from the surface of the Atlantic to 

 the bottom. 



But if the Radiolaria and Diatoms are thus rained upon the 

 bottom of the sea, from the superficial layer of its waters in 

 which they pass their lives, it is obviously possible that the 

 Globigerince may be similarly derived ; and if they were so, it 

 would be much more easy to understand how they obtain their 

 supply of food than it is at present. Nevertheless, the positive 

 and negative evidence all points the other way. The skeletons 

 of the full-grown, deep-sea Gtobigerincc are so remarkably solid 

 and heavy in proportion to their surface as to seem little fitted 

 for floating ; and, as a matter of fact, they are not to be found 



