THE HUMAN FOOT 81 



second toe. In the Gorilla, a most interesting phase is 

 seen, for while in most specimens the middle line of the 

 foot passes through the third toe, " it must be admitted 

 that many Gorillas possess the human arrangement, 

 these muscles being grouped about an axis formed by 

 the second digit " (Duckworth). 



When digits atrophy and disappear in phylogeny, it 

 seems to be the rule that their reduction starts from 

 their distal extremities ; the terminal phalanx diminishes 

 first, and the metacarpal is only affected at a much later 

 period in evolution. Metacarpal bones of absent digits 

 persist, as the well-known splint bones of the horse. It 

 is to be expected that the same order should be followed 

 in the diminishing toes of the outer side of the human 

 foot. The terminal phalanx of the fifth toe is commonly 

 a rudiment, and often it is fused to the next phalanx, 

 of which bone it then constitutes a mere distal tubercle. 

 Compared with the fingers, there has been a great reduc- 

 tion in the terminal phalanges of all the toes except the 

 big toe, and the two basal phalanges are diminished in a 

 somewhat lesser degree. In the majority of cases, how- 

 ever, the metacarpal bones have not suffered any very 

 marked atrophy, and the metacarpal formula is often 

 that which should exist for the primitive digits. Much 

 individual variation is seen in the skeletons of different 

 feet, but the metacarpal bone of the big toe is, at times, 

 shorter than that of the second, which in its turn is shorter 

 than the third; the fourth, again, is shorter than the 

 third, and the fifth shorter than the fourth. 



One very curious evidence of this skeletal condition is 

 seen in very many feet, even when the big toe is far in 

 advance of all the rest. Although a line joining the tips 

 of the toes slopes without interruption from the first to 

 the fifth, a line joining the bases of these toes does not 

 follow the same course. From the first cleft it rises to 

 the second, and from the fourth cleft it rises to the third, 

 and there is thus produced a sharp angle in the line which 



