150 



Prof. Ehrenherg on Fossil Ijifusoria. 



1 inch broad, and I inch high, which I have presented to the Royal 

 Mineralogical Cabinet ; he requested me at the same to determine the 

 forms of the animalculse, and to publish his observations together with 

 my results. Microscopical examination directly confirmed the obser- 

 vation of M. Fischer, that the Kieselguhr of Franzensbad consisted 

 almost entirely of NaviculfE ; and the great transparency and clear- 

 ness of the little siliceous shields made it indeed probable that an in- 

 tense heat had caused their accumulation from a more voluminous 

 combustible substance. But the opinion that they have belonged to 

 the bottom of a sea is improbable, since the chief part of the forms, 

 both from their figure and size, as well as from the number of theiv 

 inner stripes, agree very exactly with the Navicula viridis now living 

 in all the fresh water around Berlin, and widely diffused in other parts. 

 In the sample of ihe peat-bog there were also to be perceived Naviculee, 

 which, though mostly different from those of the Kieselguhr, were 

 still living species, and in quite a different proportion to one another? 

 and generally in a smaller proportionate quantity in the same space. 



After this the original specimens of the Kieselguhr from the Isle of 

 France, and the Bergmehl from San Fiore in Tuscany, in the Muse- 

 um of Berlin, Avhich had been chemically analysed by Klaproth, and 

 to which were still attached (he descriptions in his handwriting, were 

 microscopically examined. It was found that these substances also 

 consisted almost wholly of several different forms of fossil infusoria, 

 so that the whole siliceous contents given by Klaproth are to be assign- 

 ed to the infusoria shells. 



As early as the year 1834, I announced to the Academy, in the ap- 

 pendix to my third paper on Organization, that, after having examined 

 with M. Henry Rose the discovery made by M. Kiitzing, that the 

 shields of the Baciilaria consist of silex, this fact was fully establish- 

 ed, not only for these, but also for other living forms ; a fact which the 

 observations of M. Fischer, and my examination of the Kieselguhr ana- 

 lysed by Klaproth, confirm anew. 



As the interest of this pheenomenon appeared to be great, I com- 

 pared several other siliceous and earthy substances from the Royal 

 Mineralogic'il Cabinet, which Professor Weiss had the kindness to 

 place at my disposal, without however being able to forward the ob- 

 ject of the research. At a fortunate moment it occurred to me that 

 such siliceous shields might be in use in the arts as polish, like the 

 siliceous shavegrass, Equisetum. I purchased therefore in Berlin 

 several kinds of tripoli and polishing earths for examination. I ex- 



