28 Size of Articular Sui'faees of Tjong Bones 



Let lis now compare llic curves. At lirst siglit they give no hint of 

 the difTerence which analysis reveals. The curves of the joints show an 

 original overlapping in the order in which they are given of 78.25, 75.75 

 and 78.25 per cent repectively. The curve of the length of the humerus 

 shows 89 per cent overlapping, and that of the femur 82 per cent, but 

 in the case of the joints the amount of overlapping was wonderfully 

 reduced by the elimination of a few stragglers, respectively 4.75, 4. and 

 2.25 per cent, the percentages of overlapping dropping to 16.80, 17.71 

 and 28.90 of the remainder. In the tables of the length a much larger 

 elimination brings about much less satisfactory results. Thus with the 

 humerus the elimination of 15 bones (7.5 per cent), reduced the over- 

 lapping of the remainder only to 41.62 per cent; and with the femur 

 the rejection of 15 bones (7.5 per cent) still leaves the overlapping of 

 the remainder at 46.49 per cent. This is a very significant diflference. 



Thus it is demonstrated that the difference in the size of the articular 

 surfaces in the sexes is very much more marked than that of the length 

 of the respective bones. Altliough I have not established it by figures, 

 I have no hesitation in saying that it is also much more marked than the 

 difference in the thickness of bones. A striking illustration of this is 

 furnished by the photograph (Plate VI) of a male and a female humerus, 

 side by side, so placed as to show the articular heads as well as possible. 

 There is very little difference in the length and in the thickness, but the 

 much greater size of the joint shows at a glance which is the male. 

 What is most interesting is that the male bone came from the body of a 

 very puny young man of nineteen, who being blind, had passed his life 

 in an almshouse doing very little work. I remember him particularly 

 from the fact that he had but one kidney. My personal recollection of 

 the body of the woman from which the female bone was taken is less 

 sharp ; but she is said to have been of uncommonly powerful make. The 

 muscular ridges on the bone confirm this, yet a glance at the head is so 

 conclusive that it is needless to mark which is which. 



I have devoted a good deal of time to the glenoid cavity of the scapula, 

 and more or less to other joints in the extremities. Although I cannot 

 speak by the book, I feel very sure that the law which is deduced from 

 the humerus and femur will be found to apply, though perhaps with 

 more exceptions, to all the joints of the extremities. It should not need 

 to be said that it is the province of such a law to be a guide to the expert 

 who will apply with discretion. Absolute certainty as to the sex of bones 

 does not exist in all cases. The judgment matured by long observation 

 is certainly better than any rigid adherence to a mathematical law. None 

 the less, in many cases, the law of the relative smallness of the female 



