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 ferrugiriea 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 muriatic acid, but no longer form 

 such evident articulated threads as in the living animal. Jf I compare 

 it, when its fibres are disjointed, with the Gaillonella distans in the Po- 

 lirschiefer, I find no reason to consider the phaenomenon 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 Gaillonella fer- 

 Tuginea. These Gaillonellae 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, to which 

 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. 



