INTR on UCTION 39 



but Siberia. On investigating its mineralogical compo- 

 sition, Dr. Tornebohm, of Stockholm, came to the con- 

 clusion that the greater part of it must be Siberian river 

 mud. He found about twenty different minerals in 

 it. " This quantity of dissimilar constituent mineral 

 parts appears to me," he says, " to point to the fact 

 that they take their origin from a very extensive tract 

 of land, and one's thoughts naturally turn to Siberia." 

 Moreover, more than half of this mud deposit consisted 

 of humus, or boggy soil. More interesting, however, 

 than the actual mud deposit were the diatoms found in 

 it, which w^ere examined by Professor Cleve, of Upsala, 

 who says : " These diatoms are decidedly marine {i.e., 

 take their origin from salt-water), with some few fresh- 

 water forms which the wind has carried from land. The 

 diatomous llora in this dust is quite peculiar, and unlike 

 what I have found in many thousands of other speci- 

 mens, with one exception, with which it shows the most 

 complete conformity — namely, a specimen which was col- 

 lected by Kellman during the Vega expedition on an 

 ice-floe off Cape Wankarem, near Bering Strait. Spe- 

 cies and varieties were perfectly identical in both speci- 

 mens." Cleve was able to distinguish sixteen species 

 of diatoms. All these appear also in the dust from 

 Cape Wankarem, and twelve of them have been found 

 at that place alone, and nowhere else in all the world. 

 This was a notable coincidence between two such re- 

 mote points, and Cleve is certainly right in saying : 



