68 THE HISTORY OF CREATION. 
and phylogeny, which I have already (p. 10) claimed as 
one of the strongest pillars of the Theory of Descent. No 
one before had so distinctly stated as Agassiz did, that, of 
the Vertebrate animals, fishes alone existed, at first, that 
amphibious animals came later, and that birds and mam- 
mals appeared only at a much later period; further, that 
among mammals, as among fishes, imperfect and lower 
orders had appeared first, but more perfect and higher 
orders at a later period. Agassiz, therefore, showed that 
the paleontological development of the whole Vertebrate 
group was not only parallel with the embryonic, but' also 
with the systematic development, that is, with the graduated 
series which we see everywhere in the system, ascending 
from the lower to the higher classes, orders, ete. 
In the earth’s history lower forms appeared first, the 
higher forms later. This important fact, as well as the 
agreement of the embryonic and palzeontological develop- 
ment, is explained quite simply and naturally by the 
Doctrine of Descent, and without it is perfectly inex- 
plicable. This cause holds good also in the great law of 
progressive development, that is, of the historical progress. 
of organization, which is traceable, broadly and as a whole, 
in the historical succession of all organisms, as well as in 
the special perfecting of individual parts of animal bodies. 
Thus, for example, the skeleton of Vertebrate animals. 
acquired at first slowly, and by degrees, that high degree 
of perfection which it now possesses in man and the other 
higher Vertebrate animals. This progress, acknowledged 
in point of fact by Agassiz, necessarily follows from Dar- 
win’s Doctrine of Descent, which demonstrates its active 
causes. If this doctrine is correct, the perfecting and diver- 
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