ECONOMIC IMPORTANCE OF DIATOMS — MANN. 381 



rare form known as C ampylostylus striatus was recently rediscovered 

 in an irrigation ditch leading from the Everglades, in Florida. It 

 was first found by Mr. Shadbolt, of England, on some mahogany logs 

 shipped to London from the shores of Honduras; in other words, it 

 is a Gulf of Mexico diatom. 



An argument, and doubtless a valid one, to support the theory of 

 Prof. Nansen that a current passes northward from the Bering 

 Strait across the north polar region and southward along the western 

 shores of Norway is based upon the fact that the diatom flora of 

 Bering Sea was found by Prof. Nansen to be singularly similar to 

 that of Greenland and the Norwegian coast, thereby indicating a con- 

 nection between these apparently remote localities. From such ex- 

 amples as the foregoing it is reasonable to believe that when the nor- 

 mal diatom floras of the different seas have been investigated and the 

 local diatom floras of the shallower waters, and especially of the 

 rivers of the land, shall be laiown, we can tell by samples taken at re- 

 mote points of the ocean the parts of the earth traversed by the cur- 

 rent in which are foimd the specimens in question. In this same way 

 a problem of no little importance to ocean travel becomes one of easy 

 and certain solution, namely, the area of contact between the cold 

 Arctic water of the north and the warm w^aters of the Gulf Stream off 

 the coast of Newfoundland, this contact being the cause of the dan- 

 gerous fogs prevalent in that locality; for a sample of sea water 

 taken anywhere in that neighborhood must reveal at once to a diatom 

 expert whether the water came southward from the Arctic, or north- 

 ward on the current of the Gulf Stream, or is a blending of the two. 



A consideration of the economic value of the diatoms requires 

 mention of some minor uses. The large diatom beds of the western 

 part of the United States, and especially those along the Pacific coast, 

 where there are cliffs several hundred feet in height almost wholly 

 made of this material, are coming to be of commercial value because 

 of the use of this substance as a substitute for asbestos or in combi- 

 nation with asbestos as a nonconducting coating for steam pipes, as 

 a filler for refrigerators, and for many other uses where a noncom- 

 bustible material is needed. Fossil diatom deposits are also of value 

 to the art of pottery making, being combined with various other in- 

 gredients in the composition of certain grades of porcelains and 

 glass. 



There has recently come into notice another use for diatomaceous 

 earth which bids fair to become of considerable value to medical 

 science. The material is compressed into filters in the shape of 

 hollow cylinders or plates to be used for the filtration of serums, 

 toxins, and other sterile liquids of service in the modern treatment 

 of diseases. The porosity and extreme fineness of this material. 



