54 ON A PIECE OF CHALK 



and the chambers of many are filled by a soft animal 

 matter. This soft substance is, in fact, the remains 

 of the creature to which the Globigerina shell, or rather 

 skeleton, owes its existence and which is an animal 

 of the simplest imaginable description. It is, in fact, 

 a mere particle of living jelly, without defined parts 

 of any kind without a mouth, nerves, muscles, or 

 distinct organs, and only manifesting its vitality to 

 ordinary observation by thrusting out and retracting 

 from all parts of its surface, long filamentous processes, 

 which serve for arms and legs. Yet this amorphous 

 particle, devoid of everything which, in the higher 

 animals, we call organs, is capable of feeding, growing 

 and multiplying ; of separating from the ocean the small 

 proportion of carbonate of lime which is dissolved in 

 sea-water; and of building up that substance into a 

 skeleton for itself, according to a pattern which can 

 be imitated by no other known agency. 



The notion that animals can live and flourish in the 

 sea, at the vast depths from which apparently living 

 Globigerince have been brought up, does not agree very 

 well with our usual conceptions respecting the condi- 

 tions of animal life; and it is not so absolutely impos- 

 sible as it might at first appear to be, that the Globi- 

 gerinoe 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 Globi- 

 gerinoe, with the granules which have been mentioned 

 and some few other calcareous shells ; but a small per- 

 centage of the chalky mud perhaps at most some 

 five per cent of it is of a different nature, and con- 

 sists of shells and skeletons composed of silex, or pure 

 flint. These silicious bodies belong partly to the lowly 



