PROF. EHRENBERG ON FOSSIL INFUSORIA. 403 
ganic being, containing a yellow ochre colour, in which there is pro- 
bably a great proportion of iron, in the same manner as phosphate of 
lime is contained in the bones. By extraction of the lime, the gelatine 
of the bones retains, as is well known, its form: in the same manner 
the Gaillonella ferruginea possesses a siliceous shield, which retains 
its form unchanged after the extraction of the iron. 
I have already examined with the microscope various specimens of 
the Raseneisen from Berlin, from the Ural, from New York, and 
other places, and find the extremely voluminous yellow iron oxide 
which is attached to them, and which perhaps has originally served to 
form them, to consist also of similar connected threads in rows, which 
resemble the Gaillonella in size, form, and colour, and which are not 
destroyed by the action of heat or muriatie acid, but no longer form 
such evident articulated threads as in the living animal. If I compare 
it, when its fibres are disjointed, with the G'aillonella distans in the Po- 
lirschiefer, I find no reason to consider the pheenomenon in the Wiesen- 
erz-ochre as a different one. I received, through the kindness of 
M. Karsten, the vegetable products of the mineral water of the salt- 
works of Colberg, in which there is a yellow earthy substance, in great 
quantity, formed on the surface. At first it collects at the surface of 
the stagnant water, as I was informed, in a greenish mass, similar 
therefore to the protoxide of iron. Dried and exposed to the air it re- 
mains of a beautiful ochre yellow, and on being heated it becomes of a 
red-brown blood-stone colour. On dissolving it in muriatic acid I 
found a great quantity of iron, with remains of silex. This substance 
consists, like the marsh-ochre, of articulated threads, which separate 
into single members: it resembles also very much the Gazllonella fer- 
ruginea. These Gaillonellz are used in Colberg for iron-colour in house- 
painting. The circumstance that this production of the salt-spring col- 
lects on the surface of a yellowish green colour, and afterwards sinks 
to the bottom and changes into yellow, determines perhaps a special and 
not otherwise characterized species of the same genus*. Thus the sili- 
ceous contents of the Raseneisen, and the incombustible organic form 
of the minute bodies constituting the ochre which surrounds it, make it 
highly probable that here also an organic relation exists through in- 
fusorial formation, though only so far as to form after death, by the 
large proportion of iron they contain, a central point or nucleus, towhich 
all other iron in solution immediately around it is attracted. 
* Another quantity of this mass sent from the Diirrenberg salt-works has 
determined this question, since it appears in this that these living animals (?) 
also are always yellow; that in dying they rise to the surface of a grayish 
green colour (protoxide of iron), and in sinking to the bottom they again take 
the yellow colour. 
