no THE WONDER OF LIFE 



more available for animal use, and also break up the 

 dead bodies of animals into material that can be used by 

 plants as food. 



Besides Bacteria there are other extremely minute 

 forms of life which play an important part in the vital 

 economy of the freshwaters. Such are the Desmids, 

 Diatoms, Phyto-flagellates, and Zoo-flagellates — which 

 Prof. Lohmann of Kiel sums up in the word Nannoplankton 

 (or Dwarf-plankton). They are so minute that they pass 

 easily through the meshes of the finest silk gauze, and 

 they are best collected by centrifuging samples of the 

 water at a high rate of speed. Their importance Hes in 

 their extremely rapid multiplication and in the fact that 

 some of them are producers of the organic out of the inor- 

 ganic, while others are middlemen between the dead and 

 the living. 



The securely established general idea of fundamental 

 importance is that which Liebig did much to promulgate 

 — the idea of the circulation of matter. Apart from a 

 few permanent products like the Travertine of Tivoli, 

 the oolitic material on the shores of the Great Salt Lake, 

 and deposits of siliceous diatom- earth, everything about 

 the lake is in a state of flux. Place a box with water, 

 some mud, and some animal manure beside the fish pond, 

 and arrange it so that there may be a periodic discharge 

 from near the surface. Bacteria multiply and work their 

 way with the manure ; Infusorians multiply and form food 

 for Daphnids and other ' water-fleas ' ; these trickle in a 

 living cascade into the pond ; the fishes are fed, and the 

 fisherman's table is served. The chain may be longer or 

 shorter ; Diatoms, Rotifers, Worms and so on may share in 

 the ceaseless reincarnation of material that goes on. If the 



