310 THE HISTORY OF CREATION. 
by the laws of inheritance and adaptation ; by tribe I 
mean the ancestors which form the chain of progenitors of 
the individual concerned. (Gen. Morph. ii. p. 110-147, 371.) 
In this intimate connection of ontogeny and phylogeny, I 
see one of the most important and irrefutable proofs of the 
Theory of Descent. No one can explain these phenomena 
unless he has recourse to the laws of Inheritance and 
Adaptation; by these alone are they explicable. These 
laws, which we have previously explained, are the laws of 
abbreviated, of homochronic, and of homotopic inheritance, 
and here deserve renewed consideration. As so high and 
complicated an organism as that of man, or the organism of 
every other mammal, rises upwards from a simple cellular 
state, and as it progresses in its differentiation and per- 
fecting it passes through. the same series of transform- 
ations which its animal progenitors have passed through, 
during immense spaces of time, inconceivable ages ago. I 
have already pointed out this extremely important parallel- 
ism of the development of individuals and tribes (p. 10). 
Certain very early and low stages in the development of 
man, and the other vertebrate animals in general, correspond 
completely in many points of structure with conditions 
which last for life in the lower fishes. The next phase 
which follows upon this presents us with a change of the 
fish-like being into a kind of amphibious animal. At a later 
period the mammal, with its special characteristics, de- 
velops out of the amphibian, and we can clearly see, in the 
successive stages of its later development, a series of steps of 
progressive transformation which evidently correspond with 
the differences of different mammalian orders and families. 
Now, it is precisely in the same succession that we also see 
