Equipment.

Our adventurer starts with the following equipment of tools for making his arch as he learns to walk entirely on the ground which it must be remembered he can only do by unlearning pari passu his highly cultivated power of grasping with his foot. The old and the new cannot flourish together. The evolving foot of man is an example of a slow change in the function of an organ and consequent modifica­tion of certain structures in it. He walks with his feet turning in, or in the axis of the leg; his great toe is not in this axis but may even lie at a right angle to the foot; he rests weight on his heel and even more on the outer border of his sole, and thus the sole of one foot turns more or less towards the other; and he puts a good deal of weight on his toes which are frequently doubled over; and his gait, though erect, is never completely so, and is clumsy in appearance.

Bones: his heel-bone is relatively long and pointed and slightly arched below; the bones of his great toe are short and thick, and the other four toes relatively long and slender. You can see at once it is not primarily a walking foot. Any active boy of twelve could give him points and a beating in a race for life in the open. Further, his foot shows a much larger propor­tion of the whole foot in front of the end of the great toe than is ever seen in man. The ligaments which bind the joints of his foot together, while the muscles play upon them, are little different from those he will require for the girders of his arch, except for such a throwing out of slips, and shifting under the stresses and strains of such walking as his new gait involves.

The muscles of his leg and foot are the most important by far of his original equipment with which to set about making his arch: he could no more do this out of his present muscles than a Hebrew could make bricks without clay. It is these variable and plastic structures which are most readily adapted by use in a fresh direction or increased degree. He has the great flexors of the ankle and foot in his poorly-shaped calf (this feature might be adduced as a human character and studied in this manner if it were not of so elusive a nature) and the long flexors of his four outer toes, the special long flexor of the great toe, which in his case does not of course act in the axis of the other metatarsal bones. He is lacking here in the special detached portion of the flexor accessorius, which eventually becomes of use in maintaining the arch, between the heel-bone and the tendons of certain digits. He has, in a measure, the oblique adductor muscle of the great toe and the transverse adductor muscle, more for future use perhaps than of much present value. Like all apes and monkeys he has a peroneus longus with its tendon passing across the sole from the outer border to the base of the great toe and a peroneus brevis, both of them for everting the foot and supinating it. But here again he is lacking, for he has no little peroneus tertius, which Professor Keith speaks of as a muscle “peculiar to man” and “a special evertor of the foot”—a muscle passing from the tendons of the extensors of the toes and inserted into the little toe. He has also the tibialis anticus and tibialis posticus, the latter which flexes the ankle on the leg, and the former which also flexes it and everts the foot; he has also the special extensors of the toes.

This enumera­tion of the bony, ligamentous, and muscular possessions of gorilla C. is enough to show that, though he has little of new tools to make, he has to modify greatly those he has learnt to use so well, so that one can almost hear him echo the words of David to Saul as to his new armour.

The problem of an arch remains to be solved by eversion instead of inversion of the foot, growth in all directions of the heel-bone, and the enlargement and straightening of the great toe, and the “setting” of the foot in a certain degree of pronation and over-extension.