100 THE CANCELLI OF BONES 



external characters, but as to their microscopic 

 structure and chemical composition. 



Sir Charles Bell, in his Treatise on Animal 

 Mechanics/ alludes to the direction of the can- 

 celli in the neck of the thighbone, but his de- 

 scription will be found, on comparison, to be 

 inaccurate. Mr. Quain, in the last edition of his 

 Anatomy, 2 in referring to the cancellated struc- 

 ture of bones, states correctly the general princi- 

 ple according to which these fibres are arranged. 

 " It may be usually observed," he says, " that the 

 strongest laminae run through the structure in 

 those directions in which the bone has naturally 

 to sustain the greatest pressure." (Vol. I. p. 75.) 

 But he does not adduce a single instance in illus- 

 tration of his general proposition. 



Bourgery and Jacob, to whom the merit be- 

 longs of first calling attention to the subject, have 

 recognized its interest, and have shown that there 

 exists in several of the bones a definite relation 

 between the direction of the cancelli and the 

 weight that the bones, of which they form a part, 

 are destined to sustain. Their description of the 

 neck of the thighbone, it is believed, will be found 



1 Animal Mechanics, or Proofs of Design in the Animal Frame. 

 Published by the Society for the Diffusion of Useful Knowledge. 



2 Human Anatomy, by Jones Quain, M. D. Edited by Richard 

 Quain, F. R. S., and William Sharpey, M. D., F. R. S. First 

 American Edition. Edited by Joseph Leidy, M. D. Philadel- 

 phia : 1849. 



