108 LABORATORY MANUAL OF ANTHROPOMETRY 



4. Thumb index (a). The relative length of the thumb is obtained by 

 comparing its total physiological length (metacarp. + basal ph. -f- ter- 

 minal ph) with that of digit III, thus: 



physiol . length of thumb X 100 

 physiol. length of digit III 



5. Thumb index (6). The relative length of the thumb, as indicated 

 by its metacarpal, may be tested by comparing this latter bone with 

 the metacarpal of digit III, thus: 



physiol. length of metacarpal I X 100 

 physiol. length of metacarpal III 



6. Breadth index (separate phalanges). In this the breadth of a 

 single bone, taken in three places and averages, is compared with the 

 physiol length. 



average breadth X 100 

 physiol. length 



7. Depth index (separate phalanges). As used by Uhlbach this index 

 compares the average depth (height) with the average breadth. 



average depth (dorsal-ventral) X 100 

 average breadth 



This might also be compared with the length, as in the previous index. 



In carrying this investigation further, as is bound to be done soon, 

 both here and in the case of the foot, one sees that the number of possible 

 indices, taken with all the possibilities of comparing sums of separate 

 bones, is practically endless, and the investigator should avoid an aimless 

 multiplication of such possible data, using new indices only for some 

 definite purpose, usually to put into mathematical form some difference 

 of proportion already detected by the eye, or suspected as the result of 

 measurement. The study and comparison with the hands and feet of the 

 larger apes should here, as elsewhere, suggest certain lines of difference 

 where racial criteria are to be looked for. 



II. ANTHROPOMETRY OF THE CARPUS 



This is the most neglected region anthropometrically of the entire 

 skeleton, as thus far no definite measurements of single bones have ever 

 been established, or definite indices used. Causes for this may be 

 found in the small size of the bones, in the rarity of properly determined 

 sets of carpal bones, and also in the fact that, although small, these bones 

 are complex in form and in their mutual actions, and thus require an 

 unusual amount of data to be of use. 



It is likely that important characters may be found in the actions and 

 habitual positions of these parts, or of the wrist as a whole, the exposition 

 of which will involve more than single bones, mainly the proportions 

 of adjacent articular facets and the mechanics of the possible motions 

 between them. Again it will perhaps be sometime shown that character- 



