EXTRACTS FROM FOREIGN SCIENTIFIC JOURNALS. 
Geological. 
Upon Fossil Infusoria, by C. G. Ehrenberg. 
M. C. Fischer, the proprietor of the manufactory of porcelain at Pirkenham- 
mer, near Carlsbad, has observed that the substance resembling siliceous concrete 
(Kieselguhr), which occurs in the peat bogs near Franzensbad, in Bohemia, 
“ consists almost exclusively of the cases of several species of Naviculce , and ap¬ 
pears to be the fire-proof remains of the (in parts) intensely heated bottom of the 
ocean.” 
Together with this information M. Fischer sent me a piece of the siliceous 
mass about 2" long, 1" broad, and j" high, as well as some specimens of the peat, 
intreating me to ascertain the animal and to publish the result. Microscopic in¬ 
spection immediately confirmed the discovery of M. Fischer, that the siliceous 
concrete (Kieselguhr) of Franzensbad consisted almost exclusively of very well 
preserved Naviculce , with which some Bacillarice were intermixed, and the per¬ 
fect transparency of their siliceous cases and their freedom from all organic matter, 
renders it probable that an unusually intense heat had purified them and amassed 
them together. It is not likely that they should have originated at the bottom of 
the sea, for the majority of the animals both in form and the relative numbers of their 
striae correspond very accurately with those of the New. viridis , which is found in 
all the fresh water about Berlin as well as elsewhere. In the specimens of peat I 
could also recognise Naviculce , yet they were generally different, although still ex¬ 
isting species, fewer in relative proportion, and the prevailing forms very dissimilar. 
Original specimens of the siliceous concrete (Kieselguhr) of the Isle of 
France, and of Santa Fiora, in Tuscany, which were analyzed by Klaproth, shewed 
that they likewise consisted almost exclusively of the envelopes of Infusoria of 
several genera of Bacillarice , yet sometimes of the same, and almost all still living, 
species, in conjunction with rare siliceous spicula of fresh and sea-water sponges, 
without any intervenient binding material. This, therefore, is an additional con¬ 
firmation of Kiitzing’s discovery that the cases of the Bacillarice consist of silica. 
I myself discovered, several years ago, that the ochraceous slimy substance, 
which sometimes covers the bottom of marshy brooks and moats, and which ap¬ 
pears to have been considered as a deposit of the oxyde of iron, is a very delicate 
Bacillaria , which at a red heat becomes red like the oxyde of iron, and is very fer¬ 
ruginous, but which does not lose its form either by a red heat or upon being treated 
with acids, and consequently possesses a siliceous case most approaching to that of 
the genus Gaillonella . I therefore figured it last year, as Gaillonellaferruginea 
in plate 10 of my Infusorien Codex , which will now soon appear. All the ochre 
