On the Infiuence of Muscular Attachments, 59 



diameters in the upper, middle, and lower thirds must bear 

 definite relations to the strains which it is called upon 

 to sustain. Nevertheless, in the upper or platymeric, and 

 in the middle or pilastric sections of the shaft, there is 

 ample evidence to show that not only the special surface 

 contours of the bone, but its antero-posterior and transverse 

 diameters, may be definitely modified by the size and 

 extent of the muscular attachments. Taken by itself, the 

 ridge or elevation which marks the precise attachment 

 of a muscle may not appear very important, but the 

 accumulated influence of these attachments is sufficient to 

 produce marked differences in various diameters of the 

 bone. The recognition of this principle is of the utmost 

 importance, more especially when we have to deal with 

 unusual variation in the proportionate diameters of long 

 bones. The occurrence of such unusual proportions between 

 the antero-posterior and transverse diameters of the popliteal 

 section of the femur, together with the pronounced convexity 

 of the popliteal surface of the Trinil femur, led Dr Dubois 

 (7) to claim a unique and specific value for these appear- 

 ances. I have elsewhere shown (8) that the peculiar 

 characters of the Trinil femur are by no means uncommon 

 among the femora of different races of mankind ; but as my 

 observations were restricted to macerated specimens, the 

 importance of testing them by dissections cannot be over- 

 estimated. For this purpose the present paper records the 

 dissection of a popliteal space in which certain muscles 

 afforded noteworthy variations from their normal attach- 

 ments. The measurements of the two macerated femora 

 from this individual are also recorded, for purposes of 

 comparison. 



It may be well to note at this stage that muscular 

 abnormalities in connection with the human popliteal space 

 are by no means common, and that the general arrangement 

 of this space in the gorilla and orang does not differ in any 

 essential particular from the conditions found in man, 

 whereas in the chimpanzee (9) the popliteal surface of the 

 femur is almost entirely covered by the insertion of the 

 pubic or obturator portion of the adductor magnus muscle, 



