144 LABORATORY MANUAL OF ANTHROPOMETRY 



breadths of the proximal epiphyses of all five metatarsals, and this 

 combined breadth might very well be compared with a combined length, 

 such as those of the metatarsal, first, and second phalanges of digit 

 I. Thus the two following indices have been suggested and employed to 

 some extent. 



breadth of metatarsals I-V (proximal) X 100 



Foot index 



length of digit I; metatarsal; phal. 1; phal 2 

 breadth of metatarsals I-V (proximal) X 100 



Plantar index . 



length of metatarsal I 



As in the case of the knee, so the ankle joint, with the reciprocal 

 action of the various articular facets of the several bones involved is 

 of great importance in the study of habitual posture, and possible racial 

 differences due to environment and habit (see above, under Patella, 

 Femur, Tibia, etc). A noticeable angle, as seen from behind, is that 

 first pointed out by Volkov (1905) [Fig. 43]. For measuring this the 

 entire set of the bones involved must be accurately placed together as in 

 life, a feat impossible of accomplishment save by special treatment of 

 single specimens,* but the results show beautifully that the human foot 

 has descended from one whose sole was turned obliquely inwards, and 

 that certain of the races yet living have not progressed as far as the 

 Europeans in rectifying this. The four figures presented show the foot 

 skeleton in a natural position as seen from directly behind. The longer 

 axis of the tuber calcanei is indicated in all cases by a line, the inclination 

 of which to the long axis of the leg shows the habitual foot position. The 

 plane of the sole is in all cases set at right angles to this line. The tuberal 

 axis is thus in the chimpanzee (A) seen to be set at about 30 from the 

 perpendicular, in the gorilla (B) somewhat less; in the Veddahs from 

 Ceylon (C) the line approaches the perpendicular, and in the European 

 (D) this point is nearly attained. 



The changes shown here phylogenetically appear in succession in the 

 first two or three years of life in the human infant, who passes through 

 all the stages in the gradual straightening of the feet for erect walking, 

 from the extreme simian position at first to the characteristic adult 

 condition. The use of both the feet and legs, as well as their frequent 

 postures, give many an indication of early conditions, when these mem- 

 bers possessed a more prehensile function than in the recent species. 



Intermembral Indices 



Intermembral indices, as used thus far, concern the lengths of the 

 four principal lengths of arm and leg, as represented by humerus, radius, 

 femur, and tibia, and express the various relations shown between them 

 by the use of a certain one as a standard. The particular lengths recom- 

 mended in this work are the following:- 



*See H. VIBCHOW: Die Aufstellung der Fuss-skelets, in Anat. Am., VII, 1892. 



