ANTHROPOMETRY 125 



rare and possibly abnormal condition. A flat tibia is often accom- 

 panied by a flat fibula, and not seldom also by a platymeric (flat in 

 upper part) femur. 



The scapula presents three main shapes or types, namely, the 

 triangular or wedge-shaped; the bi-concave, with its axillary and 

 especially vertebral border concave (the "scaphoid" scapula of 

 Graves) ; and the convex, with its vertebral border markedly convex. 



Causes. — The shape of the bones is influenced by heredity, stage of 

 development, sex, muscular activity, size of body, and pathological 

 conditions. 



Heredity: There are reasons to believe that certain types of bones 

 run in families; and essentially through difi'erences in heredity there are 

 marked differences in the relative frequency of occurrence of the 

 various types in different races. 



Stage of life: During fetal life and early childhood, the shapes of 

 bones are fewer in number, and do not always correspond to the shapes 

 the bones will eventually have in the adult. Differentiation advances 

 with age and the shape of a bone is probably not fully stabilized, 

 particularly as to fluting, before advanced adult life. 



Sex: Male bones show on the whole a greater differentiation of 

 shapes than those of the females; also, some types of form are more 

 common in one sex than in the other. Most, if not all these differ- 

 ences, may, however, be due to differences in muscular activities. 



Race: The modern cultured Whites show more variation in shape of 

 bones than the Indians, and the Indians more than the Negro or 

 Negrito. The causes appear to be partly hereditary and partly 

 occupational. 



Muscular activity: Muscular peculiarities and muscular activites 

 of the individual exercise a potent influence in modifying the shape of 

 the bones. 



Size of the body: The largest and the smallest bones of any variety 

 show in general less differentiation than the average; and weak bones 

 show more uniformity than the strongly developed. 



Pathological: Very prolonged undernourishment or vitiated state 

 of blood during fetal life or childhood may undoubtedly affect the 

 general development as well as the shape differentiation of bones; but 

 no proof exists that special pathological states are responsible for any 

 special form-types of individual bones. 



The sum of the observations points to the fact that the principal 

 causes of the various shapes of the shafts of the long and bodies of 



