M ■ 



Ehrenherg'^s Discoveries — Notices of Eminent Meii. 117 



his inquiries is,* that these creatures exist at present in such 

 abundance, under favorable circumstances, that the difficuhy dis- 

 appears. In the Pubhc Garden at Berhn he found that workmen 

 were employed for several days in removing in wheelbarrows 

 masses which consisted entirely of fossil Infusoria. He produced 

 from the living animals in masses^ so large as to be expressed in 

 pounds, tripoli and polishing slate similar to the rocks from which 

 he had originally obtained the remains of such animals ; and he 

 declares that a small rise in the price of tripoli would make it 

 worth while to manufacture it from the living animals as an arti- 

 cle of commerce. These results are only curious; but his spec- 

 ulations, founded upon these and similar facts, with respect to the 

 formation of such rocks, for example, polishing slate, the siliceous 

 paste called keiselguhr^ and the layers of flint in chalk, are re- 

 plete with geological instruction. 



As the discoveries of Prof Ehrenberg are thus full of interest 

 for the geological speculator, so they have been the result, not of 

 any fortunate chance, but of great attainments, knowledge, and 

 labor. The author of them had made that 

 difficult portion of natural history, the infusorial animals, his 

 study for many years ; had travelled to the shores of the Med- 

 iterranean and the Red Sea in order to observe them ; and 

 had published (in conjiniction w^ith Prof Miiller) a work far 

 eclipsing any thing which had previously appeared upon the sub- 

 ject. It was in consequence of his being thus prepared, that 

 when his attention was called to the subject of fossil Infusoria, 

 (which was done in June, 1836, by M, Fischer) he was able to 

 produce, not loose analogies and insecure conjectures, but a clear 

 determination of many species, many of them already familiar to 

 him, although hardly ever seen perhaps by any other eye. The 

 animals (for he has prov^ed them to be animals, a!id not, as others 



had deemed them, plants) consist, in the greater number of exam- 



most 



pies, of a staff-like siliceous case, with a number of transverse 

 markings ; and these cases appear in many instances to make up 

 vast masses by mere accumulation without any change. Whole 

 rocks are comix)sed of these minute cuirasses of crystal heaped 

 together. Prof Ehrenberg himself has examined the microscopic 

 products of fifteen localities, and is still employed in extending 



* AbLandl. Kon. Ak. Wissensch. Berlin. 1838. 



