6 EXTINCT MONSTERS. 
the relative shapes of animals, and the different developments of 
the same kind of bones in various animals, and especially to the 
nature of their teeth. So great did his experience and knowledge 
become, that he rarely failed in naming an animal from a part of its 
skeleton. He appreciated more clearly than others before him 
the mutual dependence of the various parts of an animal’s organi- 
sation. ‘‘The organism,” he said, ‘‘ forms a connected unity, in 
which the single parts cannot change without modifications in the 
other parts.” 
It will hardly be necessary to give examples of this now well- 
known truth; but, just to take one case: the elephant has a 
long proboscis with which it can reach the ground, and con- 
sequently its neck is quite short; but take away the long 
proboscis, and you would seriously interfere with the relation of 
various parts of its structure to each other. How, then, could 
it reach or pick up anything lying on the ground? Other 
changes would have to follow: either its legs would require to be 
shortened, or its neck to be lengthened. In every animal, as in 
a complex machine, there is a mutual dependence of the different 
parts. 
As he progressed in these studies, Cuvier was able with 
considerable success to restore extinct animals from their fossilised 
remains, to discover their habits and manner of life, and to point 
out their nearest living ally. To him we owe the first complete 
demonstration of the possibility of restoring an extinct animal. 
His ‘‘ Law of Correlation” however, has been found to be not 
infallible; as Professor Huxley has shown, it has exceptions. 
It expresses our experience among living animals, but, when 
applied to the more ancient types of life, is liable to be mis- 
leading. 
To take one out of many examples of this law: Carnivorous 
animals, such as cats, lions, and tigers, have claws in their feet, 
very different from the hoofs of an ox, which is herbivorous ; 
while the teeth of the former group are very different to those of 
