﻿Bones of the Skeleton as an Indeo: of Nutrition. 215 



laws which govern the age-sex characteristics of the bones of 

 the appendicular skeleton. 



(e) Tlie Age-Sex Characteristics of the Skeleton in Terms of 

 Metabolism. — At the beginning of this paper, the following 

 passage was quoted from " Topinard's Anthropology : 

 " There is no appreciable difference in the skeleton in infancy, 

 and up to puberty ; its features are rather of a feminine char- 

 acter. At puberty, the line of demarcation commences, but 

 the characters are not thoroughly defined until twenty years 

 of age and upwards. At about forty-five, or upwards, the 

 distinctions of sex become less marked, and at advanced age 

 are but trifling, though the general character of the skeleton 

 is rather masculine." 



This statement rewritten in terms of metabolism, reads : 

 " There is no appreciable difference between the surface 

 texture of the bones of the male and female skeleton either 

 in infancy, or up to puberty, its features indicating a meta- 

 bolism of a favourable nutritive type. At puberty, the line 

 of demarcation commences. The metabolism of the male 

 becomes more vigorous, in other words, more katabolic. This 

 condition renders the individuation of the osteoblasts incom- 

 pletely successful, and consequently genesis is stimulated 

 particularly in regions of considerable vascular supply, such 

 as the myo-osseous articulations. A limited euryplasia results, 

 and the bones become crested and tuberculated. The meta- 

 bolism of the healthy female, on the other hand, remains 

 predominantly anabolic, and the adjustment of the osteo- 

 blastic individuation to its environment is undisturbed. 

 Genesis is not stimulated, and the normal euryplasia con- 

 tinues slight and in great measure uniform. 



In middle life, the anabolic power of all the somatic cells 

 normally tends to diminish. To this law the osteoblasts are 

 no exception, and the adjustment of their individuation to 

 their environment is disturbed or further disturbed. Genesis 

 is stimulated, and, as before, a limited euryplasia results ; and 

 necessarily the bones tend to become rougher and more 

 marked at the sites of muscular attachment. 



Abnormally, as the result of overwork causing excessive 



