326 ANNUAL OF SCIENTIFIC DISCOVERY. 



arrangement which he had assigned them, according to the develop- 

 ment of the fingers, is justified by the state of development of the other 

 organs of the Mammalia, and especially of their higher organs and 

 intellectual faculties and instincts. And I will also add, says Prof. 

 Agassiz, that mankind are not excluded from this connection, but, in 

 common with other Vertebrata, we are all at one stage of existence 

 provided with paddles or fins, which are afterward developed into legs 

 and arms. 



ON THE CANCELLATED STRUCTURE OF SOME OF THE BONES OF 



THE HUMAN BODY. 



THE following results respecting the arrangement of cancelli,* 

 have been deduced by Dr. Jeffries Wyman from the structures of 

 various bones of the human body, especially those which assist in 

 maintaining the body in its erect position: 1. The cancelli of such 

 bones as assist in supporting the weight of the body are arranged, 

 either in the direction of that weight, or in such a manner as to sup- 

 port and brace those cancelli which are in that direction. In a me- 

 chanical point of view, they may be regarded in nearly all these bones 

 as a series of " studs" and " braces." 2. The direction of these 

 fibres in some of the bones of the human skeleton is characteristic, 

 and, it is believed, has a definite relation to the erect position which is 

 naturally assumed by man alone. 



The cancelli of some bones have been described or referred to by va- 

 rious authors, but the description of the neck of the thigh-bone, as given 

 by Dr. Wyman, is different from that of any other preceding writer. 



The whole weight of the head, trunk, arms, and pelvis rests on 

 the heads of the two thigh-bones, or more or less on one of them, 

 according to the attitude of the body when in a state of rest. When 

 the body is in motion, they will sustain, in addition to this, the mo- 

 mentum of the trunk as it descends upon them in walking, running, 

 jumping, &c. The heads of the bones are themselves immediately 

 supported by the neck, the axis of which forms an angle of about 

 120 with that of the shaft of the bone, if the lower ano-le be meas- 



' o 



nred, or of 60 if the upper. The weight of the body will, therefore, 

 have an angular bearing upon the axis of the neck, and its tendency 

 will be to bend or break the neck in a downward direction. The 

 means which nature has adopted to counteract this tendency con- 

 sist, 1. In making the vertical diameter of the neck the largest, a 

 section at right angles to its axis being oval, and the long diameter 

 perpendicular. 2. In increasing the thickness of the wall of bone on 

 the under side of the neck and adjoining portion of the shaft, on to 

 which a large portion of the weight of the body is directly trans- 

 mitted. 3. In having the cancelli of each femur so arranged as to 



* Cancelli, the Latin term for lattices, or windows made with cross-bars of wood, iron, 

 &c. ; hence it is applied to the spongy structure of bones, and the term cancellated, to 

 any thing which is cross-barred or marked by lines crossing one another. 



