176 



TEXT-BOOK OF EMBRYOLOGY. 



Joint cavity 



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FlG. 153. Longitudinal section of finger of human embryo of 26 mm. (2 months), showing beginning 

 of joint cavity between adjacent ends of phalanges. (Photograph from preparation by 

 Dr. W. C. Clarke.) 



FlG 154. From longitudinal section of finger of child at birth, showing developing joint cavit^ 

 between adjacent ends of phalanges. The darker portion at each end of the figure indicates 

 the ossification center in the phalanx, the end of the latter (lighter area) being yet cartilagi- 

 nous. The dark bands at each side of the joint indicate developing ligaments. Photograph. 



