Professor Ehrenberg on Fossil Infusoria. 89 



the polishing slate. The siliceous portions of the chalk, owing 

 to their specific gravity, are gradually accumulated at particular 

 spots, and form layers of siliceous bergmehl in the chalk ; just 

 as, in the different materials composing high perpendicular 

 masses of rubbish, we see substances having the same specific 

 gravity, as mortar, fragments of porcelain, bones, &c., collected 

 together, each by itself, and gradually accumulating in horizontal 

 strata. If, then, these siliceous accumulations were penetrated 

 by a dissolving elastic, or liquid substance, they would form those 

 horizontal strata or nests, which have already attracted so much 

 the special attention of geologists, and of which some possess the 

 form of holothurioe and corals, whose vast abundance and 

 enormous size, together with their undefined form, have impart- 

 ed no small difficulty to this explanation. Some other new facts 

 regarding the extremely regular microscopic relations of the 

 chalk and porcelain earth, will be mentioned in a separate notice 

 about to be published. In menilite we can see beautifully the 

 formation of nodules of an infiltrated substance, occupying 

 almost no space, and which does not alter the stratification of 

 the including mass. 



Finally, I must here mention my observations on the precious 

 opal of Kaschau. In some fragments of the common serpentine- 

 opal of Kosemitz, and of the precious porphyry-opal of Kaschau, 

 I perceived enclosed round bodies resembling those of flint, but 

 the greater part of the mass was homogeneous. I afterwards 

 examined the matrix of the precious opal, and found that a sort 

 of lithomarge always surrounded the imbedded portions. This 

 lithomarge, under the microscope, resembles much the Gail- 

 lonella distans, as it exists in the saiigschieftr of Bilin. I have 

 frequently repeated, proved, and compared these experiments, 

 on account of the remarkable nature of the phenomena, and I 

 prefer announcing them to remaining silent ; but it is my inten- 

 tion to prosecute my researches with scrutinizing care, to 

 publish the results whenever they shall have attained sufficient 

 maturity. 



The more the partly old, partly new saying, 



Omnis Calx e vermibus, 

 Omnis Sitex e vermibus y 

 Omne Fermm e vermibus, 



