176 FOOTNOTES FROM 



several species of which are still living, and occasionally 

 seen in this country. The fossil flour which the Chinese 

 mix with their wheat or rice on similar trying occasions ; l 

 the unctuous clay which the Otomacs gather on the shores 

 of the Orinoco and Meta, and eat by way of a lonne 

 bouche after their regular meals ; the yellowish earth 

 called caouac found in Guinea, of which the negroes are 

 passionately fond ; the kieselguhr or meerschaum, found 

 in Turkey, and employed in the manufacture of pipes ; 

 and the polierschiefer, or polishing slate of Berlin, which 

 supplies the tripoli used for polishing stones and metals, 

 are all found, when subjected to the microscope, to con- 

 sist almost entirely of the silicious plates of diatomacese, 

 united together without any visible cement. The world, 

 it has been well said, is a vast catacomb of diatoms, a 

 grand herbarium in which these most ancient plants have 



1 The following particulars regarding Chinese fossil flour, adapted from 

 Ehrenberg's late great work, Mikrogeologie, may be interesting : 



" Various kinds of edible earth were known in China in very ancient 

 times, and it may be presumed that many of them are mixed or pure tri- 

 politan fresh -water bioliths, i.e., species of earths or stones, the elements 

 of which consist chiefly of remnants of microscopic living beings. In the 

 year 1839, Biot read before the Academy of Sciences in Paris a treatise, 

 containing everything that was then known on .this subject, to which his 

 son, the Oriental linguist, Biot, furnished translations from Chinese and 

 Japanese works. From Schott, in Berlin, Professor Ehrenberg obtained, 

 in addition, the following information, taken from Chinese sources. The 

 first mention of edible earth dates from the year 744 after Christ, and is 

 contained in the Chinese work, Pen-tsao-kang-mu, where it is called 

 Schimian, Stone-bread, or Mi-anschi, Bread-stone ; the article in the Japan- 

 ese Encyclopedia, which Biot has translated, is taken from this work. 

 The Pen-tsao says, according to Schott, that stones contain several sub- 

 stances which are edible, especially a yellow meal and fatty liquid, which 

 is contained in the Yu (a stone), and is therefore called the fat, marrow, or 

 mucilage of the white Yu. An earthy substance, prolonging life, and 

 called Schi-nao, is found in the very smooth stone Hoa-shi, which is sup- 

 posed to be Steatite, and may perhaps be decomposed Steatite. The Schi- 

 mian is only used as a substitute for bread in times of scarcity, when it is 



