REMARKS ON THE FIGURES OF PLATE XI. 
VERTEBRA POSSESS A LATERAL BUT NOT AN ANTERO-POSTERIOR SYMMETRY. 
“ieee we discover in any forms that character which they do possess, it is this very character present 
which indicates that the opposite character is absent if it be so. In Nature we always find that 
qualities of absolute contrast always stand opposite to each other; and thus when we see that a thing 
possesses but one absolute quality, this in itself expresses that the other absolute quality is not characterising 
the same ens. When we make use of the word fulness, we mean the opposite to void. When we say that 
the colour of a body is white, we mean the opposite to black. Day is opposite to night. The positive is 
opposite to the negative. Matter is not annihilation. Thus it is that opposite qualities or characters of 
things relate of each other. It is the same with the condition of symmetry, for when we find that any figure 
manifests this character, we instantly distinguish symmetry from asymmetry, and so the contrast becomes the 
rule of comparison. Even when a body shows itself to be symmetrically cleavable through one diameter, we 
seek to know whether it be so through another and opposite diameter. If the thing be bilaterally 
symmetrically cleft, we then ask the question, whether it be also symmetrically cleavable as to its anterior 
and posterior faces. 
All the vertebree of spinal series, from occiput to sacrum, 
are produced of homologous elements. A vertebra of 
either the cervical class, or the dorsal, lumbar, or sacral 
form, is therefore the homologue of any one of the series. 
Any vertebra of any of those classes will, when viewed 
separately, manifest the character of symmetry, and sym- 
metry is the common character of all vertebral forms. 
When we cleave through the median line, the vertebral 
figure, from the spinous process behind to the centrum in 
front, the resultant halves will fairly represent each other. 
The one half is therefore homologous with the other half 
of the same vertebra. But still further than this, we 
observe that as all vertebra present the like number of 
elemental structures, and as these structures are sym- 
metrically arranged im all, so will the one half of any 
vertebra of series represent, as to elemental quantity, not 
only the corresponding half of any other vertebra, but even 
the opposite half of any other. 
In figs. A” B’C” and D”, which represent cervical, dor- 
sal, lumbar, and sacral forms, we see that the common 
median line, marked 2, cleaves all those figures symmetri- 
cally, and just in the same way as it cleaves all the triangles 
which enclose those figures. 
So likewise in figs. A’B’C’ and D’, surrounded by the 
circle, we see that the common median line 2 cleaves 
both circles and vertebree into equal sides, semicircles and 
semi-vertebre being the resulting figures. 
The figs. A’ B”C” and D’”, enclosed by the square, 
and having the median line 2 passing through all forms, 
both of vertebree and squares, yield symmetrical sides. 
This is a common character of vertebral forms and such 
complete figures as the triangle, circle, and square. 
But the vertebra is not symmetrically cleavable by the 
median line 1, carried through its transverse diameter in 
any of the opposite figures. Neither is the triangle sym- 
In this 
condition of form the vertebra agrees with the triangle. 
The median line 2, and the transverse line 1, both 
cleave the circle and the square into equal sides, and in 
metrically cleft by the same line of cleavage, 1. 
this particular the forms circle and square differ from the 
forms vertebra and triangle, and from this it may be con- 
cluded that circles and squares have some quality of form 
which triangles and vertebre have not. 
What is this difference which characterises vertebra and 
triangles from circles and squares? It can be no other 
than this, viz., that both the vertebra and the triangle are 
minus quantities of some plus archetype figure which is 
itself cleavable, like the square and circle, from back. to 
front or from side to side, into symmetrical halves. 
The vertebral forms, figs. A BC and D, are symmetri- 
cally cleavable through their antero-posterior diameter, 
but they are not thus cleavable through the lateral or 
transverse diameter. 
Symmetry is a law which governs the development of all 
