8o THE HUMAN SPECIES 



the lateral condyle is usually the longer and the median is 

 apparently rudimentary, whereas in the anthropoid the condi- 

 tions are exactly the reverse. The human femur is usually 

 sharply bent at the top, but in the anthropoid femur the curve 

 is slight and occurs sometimes at the lower end. The anthro- 

 poid radii of the lateral knee ligaments are exactly the opposite 

 of the human. This rough anatomical sketch may be followed 

 by Professor WalkhofFs 1 " Studien iiber die Entwicklungs- 

 mechanik des Primaten-Skelets," which open with a differential 

 diagnosis of the human femur as compared with the anthropoid. 

 Walkhoff combined with his studies the application of the 

 Rontgen rays, and found, as Culmann and H. Meyer had 

 done before, that the femoral spongiosa corresponds, in its 

 tractive curves and curves of pressure, to the structure of a 

 crane. 



Now in man, according to Walkhoff, the bony crest which 

 extends from the inner angle of the neck of the femur along 

 the inner side of the bone and through the head is quantitatively 

 by far the most important and is proportioned to the great 

 pressure borne by this part of the limb in standing and walking. 

 The anthropoid femur does not possess this trajectorium ; its 

 spongiosa is coarser and its cells circular. 



Another characteristic attribute of man is the great extensi- 

 bility of the knee-joint which has been of the first importance 

 in enabling man to adopt the erect position. The platycnemia 

 of the tibia peculiar to all anthropoids, with the exception of 

 the orang, is only found in the lower races of man as may be 

 seen from the prehistoric tibiae. A similar case is that of the 

 retroversio tibiae, a retroverse position of the upper surface of 

 the tibial joint. This may always be observed, as the investi- 

 gations of Wiedersheim show, in the human embryo from the 

 third month onwards; it disappears in the sixth or seventh 

 month in children of the Caucasian race, but in the lower races 

 remains and is to be seen in prehistoric skeletons. 



The fibula of man, during the earlier phases of embryonic 

 development, is connected with the femur together with the 

 tibia. But the weight of the body having been gradually trans- 

 ferred to the tibia alone the fibula slipped, as it were, down to 



l Corr.-Blattf. Anthrop., 1904, p. 73. 



