SYMMETRICAL MARKINGS 109 



tion, the question of hemispherical elevations 

 or cup-like sculpturings is by no means 

 settled. It remains, however, that these tiny 

 objects, although so very small that many of 

 them are on the borders of our vision, or 

 even below unassisted sight, are decorated 

 with thousands of lines and markings in 

 fixed, definite, symmetrical order, each kind 

 of diatom having its own special markings 

 characteristic of its group. Very high powers 

 of the microscope reveal not only surface or 

 primary patterns, but also secondary or even 

 tertiary markings. Mr. E. M. Nelson, who is 

 deservedly looked upon as a recognised 

 authority on the study of these wonderful 

 products of Nature, admits that even with 

 the highest microscopical powers he is not 

 able to exhaust or reach the limits of design 

 in a diatom ! Complex designs involving the 

 symmetrical arrangement of many thousands 

 of lines and dots on a speck of flint that is 

 too small to be seen without a microscope ! 

 The seven artificially-constructed wonders of 

 the world, whatever they may be, are not to 



