164 J. D. Dana on Cephalization. 
transfer of members. The statement would be wholly at vari- 
ance with the very idea of cephalization. What I have asserted 
is this: that variation in grade of cephalization is manifested in 
the structure by the transfer referred to, and by this as only one 
among many mé . 
have argued that since animals have a head as their grand 
with exaltation of the cephalic extremity, is manifested not 
merely in the transfer of members to the cephalic series (thereby 
enlarging the sphere of the head), but also in the form and 
stracture of the head,—in the form and condition of the organs of 
the organs of the mouth—of the successive pairs 
of legs—of the abdomen—of the abdominal appendages; and 
in my later memoirs I have still more widely extended the list of 
characteristics that indicate grade of cephalization. a 
he laws of cephalization act conjointly with another princi 
ple in animal life:—that of the oppositeness subsisting between the 
_ cephalic or anterior and the posterior extremities of the animal struc- 
ture, which is a kind of antero-posterior or fore-and-aft polarity. 
This oppositeness or polarity is up-and-down in the plant, an 
Jore-and-aft in the animal. The fore-and-aft becomes strictly up- 
and-down in position in one animal alone—Man; and this by 
elevating heavenward the cephalic extremity, not by a change 
of the axis of symmetry to that of the plant. (See this Jour, 
xxxvi, 351. 
In view of the total misapprehension of this subject by our 
entomological critic, I may be excused for citing additional ex 
planations from an article written for a popular magazine, evel 
if they are essentially a repetition of what is contained in MY 
former papers. 
“ As the head is the seat of power in an animal, it is natural that among 
species rank should be marked by means of variations in the structure of 
the head; and not only by variations in its structure, but also in the eX 
tent to which the rest of the body directly contributes, by its members 
to the uses or purposes of the head. Cephalization is, then, simply dom- 
ination of the ficiat—cophalia domination—in an animal, as manifested 10 
the structure; and any degree of it depends on the grade of power 
