462 



LECTURE XVIII. 



upon new transformations, one bone-corpuscle after 

 another with its territory experiences the change. At 

 the border of necrosed portions of bone, when the line of 

 demarcation forms, we may distinctly observe, that the 

 surface of the bone, when viewed along the edge, becomes 

 marked with excavations, the extent of which corresponds 

 to the original cells. Upon the surface vacuities are 

 observable, which in some instances run together and 

 form holes. The bone-corpuscle which formerly occu- 

 pied the site of the hole has, in proportion as it under- 



Fig. 129. Line of demarcation in a piece of necrosed bone from a case of psedar- 

 throcase ; f a, a, a the necrosed bone with very much enlarged osseous corpuscles 

 and canaliculi ; here and there slight indications of excavations upon the surface, 

 ft, b. The vacuities, which have taken the place of the cell-districts of the bone (Cf. 

 Fig. 134), seen at the side of the object on a different level ; here and there enlarged 

 bone-corpuscles still to be seen through a layer of basis-substance which covers 

 them, c, c. Completely empty cavities. 800 diameters. 



* The drawing was made from a somewhat thick preparation, and does not repre- 

 sent one level surface, but three different planes which form, as it were, terraces, 

 one above the other. Of these c is distinctly in focus ; b is on a lower (or higher) 

 level, and is less distinctly seen ; a is lower (or higher) still, and is therefore still 

 more out of focus. Hence it is that the canaliculi (which besides are badly repre- 

 sented), are not clearly seen. From a MS. Note by the Author. 



f Necrosis (scrofulous) of the fingers in children. 



