1905.] THE OCCIPITAL CONDYLES. 7 



young Chimpanzee, the same thing prevails among apes, but to 

 a greater extent than among Men. 



Various suggestions arise in explanation of the proportions 

 of the præcondyloid and postcondyloid segments, and of the 

 transposition of the condyles backwards in relation to the 

 glabello-occipital diameter from infancy to adult life. 



It might be supposed that the proportions were influenced 

 by the general configuration of the skull as indicated by the 

 cephalic index; but we have seen that they are quite different in 

 the dolichocephalic skulls of Australian Aboriginals and of 

 Scandinavians, and likewise quite different in the brachycephalic 

 skulls of Sandwich Islanders and of Scandinavians. 



Professor Cleland has drawn attention to the size and shape 

 of the occipital condyles as features which determine the balance 

 of the skull upon the vertebral column, and therefore the amount 

 of backward and forward growth of the skull. Even if all these 

 changes could be shown to be due to the size and shape of the 

 occipital condyles, we have yet to account for their own varia- 

 tions, which cannot be regarded as accidental, but rather as 

 directly associated with the functions they have to perform. 

 Further, no matter what shape the condyles may assume, and no 

 matter how much their shape may influence the rotation and 

 balance of the skull, these facts will not explain the relation 

 which the condyles bear to the greatest antero-posterior dia- 

 meter of the skull, nor the manner in which the præcondyloid 

 and postcondyloid segments of this diameter vary in absolute 

 length. The figures show that these segments do change their 

 proportions to the greatest length from the young to the adult 

 condition, thereby indicating different rates of growth. 



To attribute such important cranial changes to the size and 

 shape of an articular surface appears to me as difficult of com- 

 prehension as if we attributed the erect attitude to initial changes 

 occurring in the hip or knee joints, rather than to regard the 

 latter as modified in association with the assumption of the 

 erect attitude, since we have evidence that this attitude is itself 

 acquired by the human subject subsequent to birth, notwith- 



