Notice of Elxrenherg's Memoir on Microscopic Life. 311 



equatorial regions belong to the same chalk formation, and they may 

 consequently be a purely organic product, in a changed condition, pro- 

 duced by the sudden or gradual operation of great volcanic action. 



14. There exists in America, (Quito, Massachusetts, Iceland,) as in 

 Europe, combustible earth, serviceable as a kind of peat, which is com- 

 posed in a great part, even to one third of the mass, of (dead ?) mi- 

 croscopic animalcules, besides the remains of plants. 



15. In America (Maine) as in Europe, and still earlier in Asia Mi- 

 nor, a technical application of the infusoria has been made for the pur- 

 poses of building stone, [bricks,] and for polishing-powder. 



16. If, besides considering minute life with regard to its distribution 

 over the surface, we attend also to its extent in depth, or in the mass of 

 the earth, we find it established by careful examinations made by emi- 

 nent American geologists, that some of the fossil beds of minute sili- 

 ceous shells belong to the tertiary formation, (Richmond.) 



With regard to the forms with microscopic calcareous shells, the re- 

 searches of the most experienced and careful geologists prove that the 

 often noticed far-extended North American [Polythalamian] limestones, 

 belong to the chalk or secondary formations.* 



17. The formation of humus is, in America as in Europe, so de- 

 pendent upon or accompanied by, invisible independent organic life, 

 that most of those lumps of earth which are overlooked, and which re- 

 main adhering to plants when they are cleaned for herbaria, contain 

 preserved whole groups of such organisms. 



18. The method of examining the portions of humus from distant 

 parts of the world proves, as the result here presented shows, that one 

 observer, with one and the same instrument, can in a short time make 

 a scientific review and comparison of the invisible minute life of all 

 parts of the earth, and under circumstances the most favorable for sci- 

 entific examination. 



As it is possible to obtain from the plants in herbaria, the smallest 

 materials used in the structure of the earth in all zones, so it is like- 

 wise possible, without change of place, to obtain similar results from 

 all parts of the ocean, by examining the matter which adheres to an- 

 chors and sounding leads, and the food consumed by various sea ani- 

 mals. The Medusse and Ascidia in particular are often filled with 

 these forms. 



Perhaps there may yet be found in the Coprolites of the transition 

 rocks (Uebergangstein) what has been destroyed during the metamor- 



* No infusorial or Polythalamian forms have yet been detected in our Silurian 

 deposits, but they abound in the tertiary and cretaceous group, and we are indebt- 

 ed to Dr. David Dale Owen, of New Harmony, for well characterized Polytha- 

 lamia from the oolitic portions of the carboniferous (Pentremite) limestone of In^ 



