1833.] 



Prof. PJhrenherg o?i Fossil Infusoria. 



155 



species, therefore not quite one-third, are either as yet undiscovered 

 but existing forms, or extinct ones. It however appears to me more 

 probable, from a comparison of my extended observations of these na- 

 tural bodies, and bearing in mind the circumstance that no extinct 

 species appear exclusively in the above-mentioned fossil relations, that 

 the new fossil species, among which is no new genus, are not extinct, 

 but still existing ones which have not yet been discovered. 



The great mass of the specimens of these animal forms is in very 

 good preservation : many of them are so beautifully preserved, that 

 I have even been able to determine from them the characters of the 

 living species more precisely ; for a direct comparison of the latter 

 showed that certain apparent characteristical distinctions are very dif- 

 ficult to be observed in the living ones, and have hitherto been over- 

 looked by me. I first discovered the apertures of the Gaillonellas in 

 the Polirschiefer, and I now perceive them in all the species of the ge- 

 nus : I have never before seen the six apertures of Navicula viridis so 

 beautifully*. 



The great sharpness and clearness of all the outlines of all these 

 siliceous shields plainly appears to have been produced by an extra- 

 ordinary red heat, which has evaporated all organic (particularly ve- 

 getable) carbon ; for the animals then lived, as at the present day, on 

 plants : at a later period the soluble earths may have become separated, 

 while the silex has better resisted all action. Werner, indeed, was of 

 opinion that subterranean fire had formed the Polirschiefer, an opinion 

 which has much in its favour. 



There is a certain remarkable preponderance in quantity of individual 

 species in most of the fossil infusoria whose localities have been men- 

 tioned. Thus the Kieselguhr from Franzensbad consists almost entire- 



* As botanists have often regarded these forms as plants, the following reasons why 

 they are considered as animals, which I have already often pointed out, are deserving of 

 remark: 1. Many Naviculse and other Bacillariai have quite a distinct, powerful, active, 

 crawling motion, by which they move and push aside other bodies much greater than 

 themselves, 2, The projection of an organ similar to the foot of a snail, and whose action 

 assists in crawling, maybe directly recognised in many forms. 3, By a close examina- 

 tion all the apertures may be seen, which may bo considered as apertures of nutrition, of 

 generation, and of motion. 4. Internal organs may be distinguished, which may be com- 

 pared with the polygastric bladders of the infusoria, and others with the crowned ovary. 

 5. The infusoria are propagated, besides the highly probable egg-formation, not by buds 

 as in plants, but also distinctly by separation, a method of propagation which is wanting 

 in all decided plant-formations, but which is observed in many decided animals. 6. Some 

 forms, whose motion is very slow, or which attach themselves like oysters, alibi d no reason 

 why they are therefore to be considered as plants. Compare the Report of the Academy 

 of Berlin, 1836, p. 34. 



