Ehrenberg’s Discoveries—Notices of Eminent Men. 117 
his inquiries is,* that these creatures exist at present in such 
abundance, under favorable circumstances, that the difficulty dis- 
appears. In the Public Garden at Berlin 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 spee- 
ulations, founded upon these and similar facts, with respect to the 
formation of such rocks, for example, polishing slate, the siliceous 
paste called keiselewhr, 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 most obscure and 
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 conjunction with Prof. Miller) 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 proved them to be animals, and not, as others 
had deemed them, plants) consist, in the greater number of exam- 
Ples, 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 
Tocks are composed 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 
PN est Se aides ec Sl 
* Abhandl. Kén. Ak. Wissensch. Berlin. 1838. 
