338 Dana on the Classification of Animals 
6. Classification hereby placed on a dynamacal or sthenic basis. — 
The laws of cephalization, as is apparent from the explanations 
which have been made, are based upon the idea that an animal 
is centralized force; and that the degree of concentration of this 
rce may be exhibited in the structure; that, consequently, the 
various grades of species or groups become apparent, to some 
extent, through size and form, and their determination is thus, 
in part, a matter of simple measurement. Dimensions or spatial 
conditions have a relation to force in the animal kingdom as 
well as in that of the celestial spheres. 
ank or grade are thus brought to the rule and plummet, and 
classification, thereby, has a dynamical basis. The distinctions 
stween groups have a dynamical or sthenic character, and all 
subdivisions in classification, when thoroughly understood, will 
have recognized sthenic relations. 
ales or lowest; and the brain in the Elephant and the Whale. 
The terms nd Mi enes are not to be u 
stood as signifying large Mammals and small Mammals, but 
Mi ife-system and weak life-system. Comparing 
the typical 
Se a 
