156 LAY SERMONS, ESSAYS, AND. RE VIEWS. [ix. 



the outward form of organic bodies so this mineral substance, 

 carbonate of lime, hidden away in the bowels of the earth, has 

 taken the shape of these chambered bodies. I am not raising a 

 merely fanciful and unreal objection. Very learned men, in 

 former days, have even entertained the notion that all the 

 formed things found in rocks are of this nature ; and if no such 

 conception is at present held to be admissible, it is because long 

 and varied experience has now shown that mineral matter never 

 does assume the form and structure we find in fossils. If any 

 one were to try to persuade you that an oyster- shell (which is 

 also chiefly composed of carbonate of lime) had crystallized out 

 of sea-water, I suppose you would laugh at the absurdity. Your 

 laughter would be justified by the fact that all experience tends 

 to show that oyster-shells are formed by the agency of oysters, 

 and in no other way. And if there were no better reasons, 

 we should be justified, on like grounds, in believing that 

 Gloligerina is not the product of anything but vital activity. 



Happily, however, better evidence in proof of the organic 

 nature of the Globigerincc than that of analogy is forthcoming. 

 It so happens that calcareous skeletons, exactly similar to the 

 Gloligerince of the chalk, are being formed, at the present 

 moment, by minute living creatures, which flourish in multi 

 tudes, literally more numerous than the sands of the sea-shore, 

 over a large extent of that part of the earth s surface which is 

 covered by the ocean. 



The history of the discovery of these living Globigerince, and 

 of the part which they play in rock building, is singular enough. 

 It is a discovery which, like others of no less scientific im 

 portance, has arisen, incidentally, out of work devoted to very 

 different and exceedingly practical interests. 



When men first took to the sea, they speedily learned to Look 

 out for shoals and rocks ; and the more the burthen of their 

 ships increased, the more imperatively necessary it became for 

 sailors to ascertain with precision the depth of the waters they 

 traversed. Out of this necessity grew the use of the lead and 

 sounding line ; and, ultimately, marine-surveying, which is the 



