I must confine my remarks chiefly to the _human_ foot. Still the anatomy of man derives so much interest from being studied in connexion with that of the lower animals, and is so much more instructive when this is done, that I cannot forbear diverging, here and there, to make a few comparisons. Let me, for a moment, draw your attention to a similarity, in general construction, which exists between the lower limbs of man, and the hinder limbs of other animals. And the comparison may be extended to the fore limbs; for however diverse may be the appearance and the mode of action of the limbs in different animals, whether they be terminated by hands or by feet, whether they move upon the ground or ply in air or water, whether they be attached to the head, as are the front fins in many fishes, or, as is more common, be situated at the fore and hinder parts of the trunk, the same plan is traceable in all. Great, indeed, is the variety of detail in nature. It is everywhere observable. No two things, however near their resemblance, are precisely alike. Yet, as I have before said, there is a remarkable adherence to unity of plan. One star differs from another star in glory, yet all appear fashioned in the same manner, and subject to the same laws. There are almost infinite varieties in the vertebrate kingdom. Each animal exhibits its own peculiarities; yet they are all formed in the same manner, and are developed upon one fundamental pattern, diverging from it in different ways according to the requirements of each. Again, though the several parts of the same animal differ from one another; yet in the skeleton the same bones which exist in one part may, as a general rule, be traced in other parts and in other animals. The bones which make up the pelvis in man are repeated in his shoulder, and, even, in his skull; and they may be recognised in the pelvis, in the shoulder, and in the skull, of all other vertebrate animals, with few exceptions. They undergo, it is true, great varieties in shape and size; but they can be shown to be the same, or, in the language of anatomists, to be “homologous.” It is highly interesting to the anatomist to trace the same bone through the different parts of the same animal, and through the various animals of the vertebrate series, and to observe the modifications which it undergoes in order to adapt it to the multiform mechanism of the several classes, to observe it sometimes dwindling, or even vanishing, and then, it may be, reappearing under some new conditions. [Illustration: Fig. 4. Human Leg.] [Illustration: Fig. 5. Horse’s Leg.]