matism, the
paralyses from lead; in the eruptions excited by iodide of potassium or
copaiba. And any large museum will contain examples of equal symmetry in
syphilitic ulcerations of the skull; in rheumatic and syphilitic deposits
on the tibiae and other bones; in all the effects of chronic rheumatic
arthritis, whether in the bones, the ligaments, or the cartilages; in the
fatty and earthy deposits in the coats of arteries."[191]

He also considered it to be proved that, "Next to the parts which are
symmetrically placed, none are so nearly identical in composition as those
which are homologous. For example, the backs of the hands and of the feet,
or the palms and soles, are often not only symmetrically, but similarly,
affected with psoriasis. So are the elbows and the knees; and similar
portions of the thighs and the arms may be found affected with ichthyosis.
Sometimes also specimens of fatty and earthy deposits in the arteries
occur, in which exact similarity is shown in the plan, though not in the
degree, with which the disease affects severally the humeral and femoral,
the radial and peroneal, the ulnar and posterior tibial arteries."

Dr. William Budd[192] gives numerous instances of symmetry in disease, both
lateral and serial. Thus, amongst others, we have one case (William
Godfrey), in which the hands and feet were distorted. "The distortion of
the right hand is greater than that of the left, of the right foot greater
than that of the left foot." In another (Elizabeth Alford) lepra affected
the extensor surfaces of the thoracic and pelvic limbs. Again, in the case
of skin disease illustrated in Plate III., "The analogy between the {184}
elbows and knees is clearly expressed in the fact that these were the only
parts affected with the disease."[193]

Professor Burt Wilder,[194] in his paper on "Pathological Polarities,"
strongly supports the philosophical importance of these peculiar relations,
adding arguments in favour of antero-posterior homologies, which it is here
unnecessary to discuss, enough having been said, it is believed, to
thoroughly demonstrate the existence of these deep internal relations which
are named lateral and serial homologies.

What explanation can be offered of these phenomena? To say that they
exhibit a "nutritional relation" brought about by a "balancing of forces"
is merely to give a new denomination to the unexplained fact. The changes
are, _of course_, brought about by a "nutriti