326 PROF. EHRENBERG ON ANIMALS OF THE CHALK 
tertiary period more identical in kind than all the other larger 
organisms. However, the knowledge of these phenomena had 
in 1837 already proceeded so far, that, besides the fossil occur- 
rence of several living species, such a considerable number of 
those which had been nowhere observed living could be enume- 
rated*, that there was no longer any reason for not consider- 
ing all the peculiar species of the fossil strata as still existing 
and only having hitherto escaped attention. The results of these 
observations also rather fell into the already formed track of 
the other fossil organisms, according to which in the deeper 
(tertiary) strata of the earth living forms occurred mingled with 
many species and genera no longer to be found. Hence, then, 
the former seemingly obvious opinion was continually more and 
more supplanted, that the collective loose Bergmehls and Kiesel- 
guhrs consisting of Infusoria were only formations of the most 
recent time and of the most superficial kind ; for there was like- 
wise in them always a considerable number of species which had 
not yet occurred living ; according to which these formations of 
Franzensbad, Sweden, Finland, &c., likewise appeared not to 
belong to the present world, but to an earlier period of the 
tertiary epoch of the earth’s formation. 
Notwithstanding this apparent reconciliation of the previous 
differences of the microscopic results from those afforded by the 
consideration of larger bodies, and notwithstanding my endea- 
yours to promote this agreement by most accurate observation, 
yet continued inquiries, instead of presenting a constantly more 
evident disclosure of new genera at the expense of formerly ex- 
isting ones, have continually extended more of the life of the 
present world into the dead mass of the former one; and the 
constantly increasing number of the now living species from the 
fossil strata, even from the lowest tertiary layers, has gradually 
awakened the thought, that the microscopic organisms, whose 
numbers and relative masses are so inconceivable, may have pre- 
eminently outlived certain great catastrophes of the earth. 
b. Physiological possibility of lony duration of life of the Infusoria. 
This result of reflection acquired increasing interest from a phy- 
siological ground, suggested by the investigation of existing 
species, for ascribing to infusorial forms a possible permanence 
* In the Memoir on the relations of Masses of existing Siliceous Infusoria, 
printed in 1837, this relation has been treated of at length, p. 3 and 4. 
