EHRENBERG ON METEORIC AND VOLCANIC DUST. 11 



On this extension of the special examination of the material, it 

 was soon found that there were in the dust several uncarbonized 

 specimens of woody fibre and other filamentary bodies resembling 

 the fine hair of animals, but these were presently recognized as 

 derived from coloured absorbent paper, being those bodies which 

 had been already falsely and rather oddly described by botanists as 

 Lepto)iiitus polychrous, although they are in fact nothing more 

 than small fragments of absorbent paper. To remove such acci- 

 dental substances the author burnt a small portion of the dust on a 

 platinum dish, and afterwards obtained a series of forty experiments, 

 twenty of them from the burnt and twenty from the unburnt substance. 



The result of the new investigations was, that of forty little par- 

 cels of the dust, each about the size of a pin's head (about half a 

 cubic line), seventeen were found to contain organic bodies some- 

 times more and sometimes less abundantly, and that in the rest of 

 the mass, minute fragments of wood from 10'" to 1'" in length were 

 recognized and separated. The following forms were found : — 



a. Siliceous-shelled Infusoria. 



1. Navicula silicula. 



2. Cocconeis, sp. n. 



IjM h. Siliceous Phytolitharia. 



3. Lithostylidium quadratum. 



4. serpentinum. 



5. Lithochaeta borealis 1 o-r i, • i: i ^ 



g 5 > biliceous hairs of plants. 



7. Spongolithis acicularis ? 



c. Soft combustible bodies. 



8. Variegated woolly fibres of absorbent paper. 



9. Fibres of dicotyledonous word, unburnt. 



The author therefore concludes — 



1. That the conditions under which these organic bodies are con- 

 tained in the meteoric dust, almost all of them being known terres- 

 trial and freshwater forms, entirely preclude the idea that they can 

 have become mixed with the dust by any accidental circumstance 

 occurring during the time of its being collected. A sailing vessel 

 from Iceland has been so long at sea before it reaches the Orkneys, 

 that the surface of all the parts whence the dust was collected must 

 have been frequently washed by the salt water. 



2. That these organic particles have not at all the character of 

 being foreign bodies included accidentally in the mass, but are 

 distributed throughout, and so intimately mixed that it would be 

 difficult to imitate artificially so perfect a dissemination. 



3. That the fibres of dicotyledonous wood appearing as uncar- 

 bonized fragments in fresh volcanic dust, is no objection to this 

 substance being produced by the same catastrophe in Iceland as that 

 from which the glassy particles in the dust-cloud were derived, since 

 the incalculable force of steam would easily tear into the smallest 

 fragments all the vegetable substances of the turfy surface of the 

 district where the eruption took place, and convert them so rapidly 



