WORLD-BUILDERS. 163 



Nasmyth hammers. Sir James Koss found the sur- 

 face of the Southern Sea bordering that ice-barrier 

 thick with a brown scum, which consisted almost 

 exclusively of living Diatomacece ; and Dr Joseph 

 Hooker remarked that they were rendered peculiarly 

 conspicuous by their becoming enclosed in the newly 

 formed ice, and by being washed up in myriads by the 

 sea on the pack and bergs, everywhere staining the 

 white ice and snow with their own ochreous brown 

 hue. A deposit of mud, consisting mainly of the flint 

 shells of these beings, extending not less than four 

 hundred miles in length and a hundred and twenty in 

 breadth, was found at a depth of from two hundred 

 to four hundred feet, on the flanks of Victoria Land, 

 in 78 south latitude. The depth and thickness of 

 this deposit could not be conjectured ; nor do we know 

 anything of the rate at which it increases ; but obser- 

 vations in future ages may determine this from now 

 known data, and an estimate may then be formed of 

 the scale on which these laborious operators turn out 

 their work. 



Every frustule of the Diatomacece adds its quota to 

 the solid structure of the globe, and that whatever the 

 destiny of the living being. It is not only those which 

 die what a jury of Diatoms might cah 1 a natural death, 

 not only those that fall quietly to rest in their bed, 

 the mighty quiet bed of the ocean, that are adding 

 their shells to the globe-crust: those incalculable 

 millions of millions that form the sustenance of mil- 

 lions of hungry and predatory animals, ah 1 come to the 



