[Illustration: Fig. 73.--Flexures on foot of vulpine phalanger.] [Illustration: Fig. 74.--Foot of loris.] [Illustration: Fig. 75.--Foot of ring-tailed lemur.] Meaning. Whatever be the meaning and origin of these flexures they are not mere folds such as one makes in a garment and leaves it so. Action, function and fitting of the structures of the hand and foot are involved in their history. They may loosely be termed “ergographs” without any reference to the exact measurement of work done. No proper idea can be formed of them if the original function and evolution of the walking-pads of earlier mammals be omitted. If one goes back and back until one reaches some lowly marsupial as a _vulpine phalanger_, or insectivore such as a common _hedgehog_, one may even metaphorically see these animals being fitted by a shoemaker with rude shoes or walking-pads for the better locomotion on or under ground, or in the branches of trees. These pads are projecting masses of hard fat with fibrous tissue interspersed and they early become fitted or adapted _to_ or _by_ the use to which they are put. It is impossible to suppose that certain rudimentary pads are devised by selective processes prior to the altered habits of walking of the animal that acquires them. From the shoemaking point of view the fashion is rough and generalised, and the changing habits of the animal adapt the shoe by degrees to the function employed, much as many a private soldier knows to his cost that he has had to adapt slowly and painfully his army boot to his particular foot. This process in an early pedestrian mammal involves the breaking up and limiting of the rudimentary pads by sulci in the dense skin, and the process of struggle and adjustment between the pads and their bordering furrows issues in the characteristic flexure of each mammal. From experiences in the human body one knows how easily fibrous adhesions between the skin and deeper parts, notably in cases of Dupuytren’s contraction of the palmar fascia, are formed by close apposition of the two layers. Such adhesion is precluded when much movement of the part occurs, but _ex-hypothesi_ the rudimentary flexures are distinguished by absence of movement, and the conditions for fixing down the deeper layers of the skin to the bones beneath are clearly present. That these are not indifferent structures is evident from what Macalister says, and though they be small or even trivial may be held to have acquired at some time or other selective value. Their early stages would necessarily be too tentative, varied and slight to acquire such value. [Illustration: Fig. 76.--Foot of squirrel-monkey.] [Illustration: Fig. 77.--Foot of macaque.] [Illustration: Fig. 78.--Foot of gibbon.] [Illustration: Fig. 79.--Hand of chimpanzee.]