38 DROPS OF WATER. 



detached amidst the chalk. Whence this great 

 quantity of a substance, which seems to be charac- 

 teristic of the chalk formation ? The supposition 

 is, that it has been derived mainly from siliceous 

 coverings of animalcules ! The remains of many 

 of these minute and humble animals have been 

 discovered in the chalk, some of them being the 

 first animals which yet exist in the species upon 

 earth. It has also been found that the flints 

 invariably include the remains of some sponge, 

 or other humble animal form, the lineaments of 

 which are often beautifully preserved amidst the 

 dark glassy substance, and may be detected by 

 a microscope, if not by the naked eye. Now, if 

 the silex from the coverings of the dead Infu- 

 soria, were in solution amidst the settling sub- 



