THE CANCELLI OF BONES 119 



as co-exist. 1 As to the individual bones, it has 

 been shown in what direction force or weight is 

 applied to them, and in what direction the cancelli 

 are arranged within them. On the lumbar verte- 

 bra there is vertical pressure ; within, the principal 

 fibres are also vertical. On the neck of the thigh- 

 bone the weight of the body is applied obliquely 

 to the end of an arm ; within it there is a com- 

 bination of fibres, giving strength with lightness, 

 which forms a frame mechanically adapted for 

 resisting the weight which rests upon it. On the 

 astragalus the pressure again is vertical, but this 

 bone rests on two others, one below it, the os 

 calcis, and the other in front, the scaphoides; 

 within there exists two series of cancelli direct- 

 ing the pressure on the surfaces of support, and 

 very nearly the same description applies to the os 

 calcis. A certain direction of fibres in all these 

 instances co-exists with a certain direction, or cer- 

 tain directions, of the transmission of pressure. 

 From this constant association of structure and 

 function, the inference seems unavoidable, that 

 they are means and ends. 



The next subject for consideration is, as to the 

 existence of some more general condition to which 



1 " Whatever may become of hypothesis, the man who has 

 made a permanent addition to the knowledge of facts has ren- 

 dered an imperishable service to science." GEORGES CUVIER, 



Anatomie Comparee. 



