86 THE DOCTRINE OF DESCENT, 
skill that he undoubtedly approached the object at which 
he aimed—the Natural System. He supplied the first 
reliable information respecting extinct species. With 
regard to those which had replaced them in subsequent 
periods, he was not, as is generally supposed, an un- 
qualified partizan of new creations, but he refrained 
from any fixed opinion. “I will not,” he~ says,” 
“positively affirm that for the production of the present 
animals a new creation was required. I merely say 
they did not live in the same locality, and must have 
come from elsewhere.” Geoffroy Saint Hilaire, on the 
contrary, does not doubt that the animals now living are 
descended, by an unbroken succession of generations, 
from the extinct races of the antediluvian age. 
Cuvier’s method involved the danger of introducing 
dogmatism into natural science, and it is therefore 
justifiable to refer in this place to one of Cuvier’s imme- 
diate disciples only recently deceased—Louis Agassiz, 
who in the most rigidly didactic manner adheres to the 
systematic categories, and invests them with fine-sound- 
ing definitions as “embodied creative ideas.”'® Accord- 
ing to him, species belong to a particular period in the 
world’s history, and bear definite relations to the physical 
conditions predominant at the time, as well as to the 
contemporaneous plants and animals. Species are 
founded on well-defined relations of individuals to one 
another and the world in which they live, as well as on 
the proportions and mutual relations of their parts, and 
on their ornamentation. 
Individuals, as representatives of species, bear the 
closest relations to one another; they exhibit definite 
relations also to the surrounding element, and their 
