NATURE'S JEWELS. 159 



be precious in a natural sense not, indeed, as we 

 speak of " precious stones," but rather as we regard 

 the prime essentials of existence even as air and 

 water, which, although so common, are yet so 

 precious that we cannot do without them. 



But we are somewhat anticipating our subject, 

 for what we have hitherto spoken of are only the 

 " remains," so to speak, of the Diatoms the outer 

 covering the external skeletons the shields, 

 plates, shells, and valves, as they are respectively 

 named. And as to these, one may adopt the language 

 of Lane Clarke, and say, "As the wondering 

 astronomer discovers the infinite worlds revealed 

 in unfathomed space, and sees star after star arise 

 in countless myriads within the dim and distant 

 nebulse ; as his mind bows down overwhelmed by 

 the sense of the Omnipotent Creator's dominion 

 and guidance of all those glorious orbs: even so 

 the microscopist bends in astonished awe before 

 the infinitude of God's works in the uncountable 

 varieties and exquisite beauty of the minute 

 Diatoms." Externally the Diatom consists of two 

 plates or valves, united or kept in opposition to each 

 other by a connecting zone or rather, by two 



