Development of Animal Organization. 213 
this theorem is that the present species of plants and animals 
are of a more recent date, that they are not of the same antiquity 
as plants and animals in general in the history of our planet. 
If we suppose that the now living species of organic beings lived 
already at the same periods to which the remains of older forma- 
tions belong, then it is perfectly inexplicable why we do not find 
the remains of them, or at least of many of them, in all the 
different strata. If an antiquary finds in some old burial-places 
only weapons and instruments made of stone or bone, in other 
sepulchres only bronze implements, he is led naturally to the 
conclusion that these remains belong to different periods of 
civilization ; but he would be inconsiderate and devoid of all 
justification if he admitted that the people in whose sepulchres 
he had found only stone implements were likewise in the posses- 
sion of bronze weapons, which he did not find. Inthe same manner 
palzontological questions are to be discussed. When one of our 
contemporaries* preposed the opinion that, from the first begin- 
ning of organization upon our planet, all species of plants and 
animals were created at once, the now living forms as well as 
the others the remains of which are found in the strata of moun- 
tains, and that these various strata were formed after the crea- 
tion of all these species of organic bodies, many of which died 
out, some in a remote, others in a more recent period,—when, I 
say, one of our contemporaries proposed this opinion, no anta- 
gonist arose, and the paradox passed away hardly remarked. 
Evidence to the contrary was too strong, and in such a case 
silence is preferable to the refutation of palpable error. Like 
silence is also better than demonstration of what is evident of 
itself. 
It would require nearly a perfect abnegation of all knowledge 
gathered by observation if we did not admit these two funda- 
mental results of paleontological investigations,—first, that 
there existed formerly on our planet other species of plants and 
animals than those which are now living; and in the second 
place, that the now living species of plants and animals did not 
exist from the beginning of life on earth. As to the last thesis, 
we are authorized to say with confidence that our now existing 
species of Mammalia did not live at the same period with the 
Anoplotheria and Paleotheria, the bones of which are dug up in 
the Tertiary formation of the neighbourhood of Paris. The 
fishes now swimming in European seas did not swim in the 
waters whose muddy deposits gave origin to the copper-slate of 
Maesfeldt, &c. These conclusions are the results of comparative 
inquiries. If the species now living existed at those periods, 
_* Kutorga, Einige Worte gegen die Theorie der stufenweisen Entstehung 
der organische Wesen auf der Erde. Bonn, 1839, S. 24. 
