arms, the lower to the legs, that in each jaw the same bony divisions
exist as in the limbs, the teeth, for instance, corresponding to the
claws (_loc. cit._, p. 408). It led him to distinguish "two animals" in
every body--the cephalic and the sexual animal. Each of these has its
own organs; thus "in the perfect animal there are two intestinal systems
thoroughly distinct from each other, two intestines which belong to two
different animals, the sexual and cephalic animal, or the plant and the
animal" (p. 382). The intestine of the sexual animal is the large
intestine; the lungs of the sexual animal are the kidneys, its glottis
is the urethra, its mouth the anus. So, too, the mouth is the stomach of
the head. On another line of thought the sternum is a ventral vertebral
column. Limbs are connate ribs, the digits indicating the number of ribs
included (_cf._ Duges, _supra_, p. 88).

J. F. Meckel[152] discusses "homologies" of this kind in the thorough and
pedestrian way so characteristic of him. Not only, he says, are the
right and left halves of the body comparable with one another, but also
the upper and the lower, the dividing line being drawn at the level of
the diaphragm. The lumbar complex corresponds to the skull, the anus to
the mouth, the urino-genital opening to the nasal opening; in general,
the urino-genital system corresponds to the respiratory, the kidneys to
the lungs, the ureters to bronchi, the testes and ovaries to the thymus
(he had observed the physiological relation between the development of
the thymus and the state of the genital organs), the prostate and the
uterus to the thyroid gland, and the penis and clitoris to the tongue.
The fore-limbs and girdle correspond in detail with the hind limbs and
the pelvis--a point already worked out by Vicq d'Azyr; the dorsal and
ventral halves of the body are likewise comparable in some respects, the
sternum, for example, answering in the arrangement of its bones, muscles
and arteries to the vertebral column. The skeleton of each member is in
some respects a repetition of the vertebral column.

His brother, D. A. Meckel,[153] worked out an elaborate comparison between
the alimentary canal and the genital organs, basing the legitimacy of
the comparison upon early embryological relations and upon the state of
things in Coelentera, where genital and digestive organs occupy the same
cavity. In his view the uterus corresponded to the stomach, the vagina
to the oesop