102 GRADATION AMONG ANIMALS. 
lectual one? These correspondences are corre- 
spondences of thought,—of a thought that is 
always the same, whether it is expressed in the 
history of the type through all time, or in the life 
of the individuals that represent the type at the 
present moment, or in the growth of the germ of 
every being born into that type to-day. In other 
words, the same thought that spans the whole 
succession of geological ages controls the struct- 
ural relations of all living beings as well as their 
distribution over the surface of the earth, and is 
repeated within the narrow compass of the small- 
est egg in which any being begins its growth. 
