10 MICROSCOPICAL OBJECTS FOUND 



scopic Corallines, siliceous Infusoria, spicula of 

 Sponges, and detached frustules, belonging to the 

 interesting group of Diatomacese. Another part 

 was composed of the small comminuted fragments 

 of Echinoderms, and some of the larger Molluscs, 

 the latter consisting chiefly of detached and broken 

 prisms of carbonate of lime, such as a very small 

 geological change would convert into what would 

 appear inorganic semi-crystalline atoms. Of truly 

 inorganic fragments, excepting a few sand grains 

 I have seen few or no traces. There are many 

 which I once conceived to be such, but one 

 after another, I have been able to identify them 

 all, and am now led to believe that the whole 

 deposit owes its existence to the steady and 

 continued operation of vital causes. It is not 

 intended to assert, with M'Culloch, that lime is 

 an organic product, but that, so far as portions 

 of the Levant mud are concerned, living organ- 

 izations have been the sole instruments by which 

 lime and silica have been separated from the water 

 of the seas, and converted into an insoluble form, 

 their constant accumulation causing the existence 

 of a calcareous sediment, which only requires a 

 sufficient length of time, without the interference 

 of any great physical disturbing causes, to produce 

 strata of indefinite thickness. 



