microscope was invented this mystery, as well 

 as many others, was solved. The chemical 

 components of chalk are precisely the same as 

 those of limestone. The microscope shows 

 that chalk is almost wholly a product of very 

 small organized shells. The animals who are 

 the architects of the chalk cliffs are called 

 " f oraminif era " bearing shells perforated 

 with little holes. The chief difference be- 

 tween chalk and limestone seems to be in the 

 size of the shells of which they are respectively 

 made up and in the manner of the bonding of 

 these shells together. The shells in a lump of 

 chalk are held much more loosely than those 

 in a lump of limestone. These intrepid 

 workers are still actively changing the struc- 

 ture of the bottoms of seas and oceans, and 

 forming new islands, which in turn become the 

 substructure that supports new life, animal 

 and vegetable. And when we consider the 

 great part performed by these microscopic 

 architects and builders it is not a misnomer 

 to speak of the building of a world. 



