402 PROF. EHRENBERG ON FOSSIL INFUSORIA, 



the infusoria of which it consisted, that it is evident that the leaf-tri- 

 poli sold at Berlin comes from Bilin in Bohemia, through Dresden. A 

 similar stone to this is the Polirschiefer found at Planitz near Zwickau, 

 if indeed the locality of the specimen examined by me be correct. But 

 the Klebschiefer from Montmartre, which Klaproth has analysed, exhi- 

 bited only doubtful traces of infusoria shields. The appearance of the 

 fossil infusoria in the form of the Polirschiefer of Bilin is plainly of 

 great importance to our further researches into geognostical rela- 

 tions. In the same slate are found the impressions of an extinct fish, the 

 Leuciscus papyraceus of Bronn, (according to Agassiz,)and several im- 

 pressions of plants, probably belonging to the tertiary formation. 



I had been inclined, even before these researches, to assign a great 

 influence in the origin of the Raseneisen (bog-iron-ore) to an infusorium 

 discovered by me in 1834, and of which I have, in April 1835, given an 

 engraving in Plate X. of my Codex of Infusoria, under the name of 

 Gaillonella ferrugmea, which is perhaps the same as the Hygrocrocis 

 ochracea of botanists. The minuteness of these corpuscles deterred me 

 however from publishing this important circumstance ; but since the 

 discovery of so many and various shield-infusoria as stone masses, and 

 since I have found that even the animalculae which almost entirely form 

 the Polirschiefer of Bilin are also a species of the genus Gaillonella, I 

 no longer hesitate to add this observation to the rest. That the for- 

 mation of the Raseneisen, or of the Wiesenerz (meadow-earth), as 

 a continual phaenomenon excites great attention, and has given rise 

 to many but not sufficiently explanatory theories, is well known. I 

 have every spring observed in the marshes, particularly in the turf di- 

 stricts about Berlin, large quantities of a substance of a very deep ochre 

 yellow, sometimes passing into flesh red, often covering to a great ex- 

 tent the bottom of the ditches from one to several feet deep, and much 

 developed in small holes and in the footsteps of animals grazing. This 

 mass is extremely delicate, and without any consistency, dividing itself 

 at the least touch into an indefinite number of parts. Where it has 

 become di-y, after the evaporation of the water, it appears exactly like 

 oxide of iron, for which it has been formerly often mistaken. We per- 

 ceive however under the microscope, with a moderately high magnifying 

 power, extremely slender articulated threads, the members of which 

 measure only xo\yo of a line, and in which the yellow colour is inherent. 

 At the beginning of last summer I satisfied myself that these slender 

 articulated threads do not lose their form in a strong red heat, but the 

 colour changes to a red-brown, which is exactly that of iron-ochre. 

 It was found that by the application of muriatic acid the colour was 

 dissolved, without the articulated threads being changed : in the solu- 

 tion precipitated iron was cleai'ly visible. There is also one of the 

 genus Gaillonella, very similar to the Bacillaria, but a very minute or- 



