31)0 Geological Memoirs. 



have become associated with the lava in which it was found, frag- 

 ments of the adjacent rock existing in it in considerable number. 



The only example of any distinct relation of microscopic organic 

 bodies with recent volcanic phsenomena was one recorded by M. von 

 Humboldt, and occurring near Quito, where an extensive volcanic 

 mud-eruption distinctly presents the phenomenon of minute organic 

 bodies, especially those of vegetable origin, proceeding from the in- 

 terior of a volcano, apparently from a great depth and in direct asso- 

 ciation with those volcanic effects which have upheaved mountain 

 masses. 



It has however lately become an important object of investigation 

 to learn where we are to seek for the first traces of organic life, and 

 although for some time calcareous rocks have alone been considered 

 as affording distinct evidence of its existence, on account of the 

 change effected in the siliceous parts of infusorial animalcules in 

 fused rocks, the anticipations of the author that these remains were 

 more permanent than had been supposed, are fully borne out by the 

 facts about to be recorded, since he is now able to announce that 

 pumice both in its normal state and in powder, volcanic tuff, vol- 

 canic conglomerate, trass, decomposed porphyry and porcelain earth 

 or volcanic ashes, as well as clink-stone, and apparently the crumbling 

 marecanite-tuff, besides the various volcanic fused and erupted rocks, 

 have one after another and in rapid succession been found to exhibit 

 a direct and necessary relation with the most minute forms of or- 

 ganic existence, and that such is the case from whatever part of the 

 earth these rocks are obtained. 



The progress of the investigation is as follows : — 



A specimen of very white siliceous earth of loose texture and 

 small specific gravity, obtained from the foot of the volcano ' Hoch- 

 simmer' near the lake of Laach on the Rhine, was in July 1844 for- 

 warded to the author by Prof. Noggerath of Bonn for microscopic 

 investigation, the specimen being suspected to contain infusorial 

 remains. It appeared on examination that the whole mass, with the 

 exception of a few grains of quartzose sand, consisted of siliceous 

 infusorial cases, while the peculiar association of species and their 

 diminutivencss, and especially the remarkable preponderance of Pin- 

 nularia viridula, induced the author to conclude that there existed 



