REGENERATION AFTER EXARTICULATION 15 
staining reaction. ‘The expansion of the axial cartilage finally 
brings it into contact with the embryonal cartilage and they 
become so closely united as to appear almost continuous (fig. 3). 
The peripheral cartilage (fig. 3, Per.C.) meanwhile has spread 
to the distal end of the bone (B.f.) and there unites with the 
axial cartilage (Az.C). This results in a continuous cap of 
cartilage covering the distal end of the femur, and extending 
proximally for some distance. Figure 4, E’p.f.n. from a much 
later stage than figure 3, shows this new cap. From it, the new 
epiphysis of the femur is formed and also the new bone of the 
intermediate zone between epiphysis and shaft which was lost 
in the early resorption process. A portion of the marrow cavity 
M.c.n. can be seen extending into it.7. At Os.n., new bony 
tissue is spreading into the cartilage. This new ossification 
is shown under high magnification in figure 10, which is taken 
from the same region of a neighboring section. The new bone 
(Os.n.) appears as a mass of interlacing fibers extending through 
the matrix of the cartilage (C.n.). In this process, the cartilage 
cells are gradually enclosed by the newly formed bone and con- 
verted directly into bone cells. Three such cells are shown at 
Os.c. Portions of the marrow cavity (M.C.) and bone of the 
shaft (B.f.) are included in the figure. Between the shaft and 
the marrow cavity some of the old calcified cartilage remains 
(compare fig. 3, C.c.). A direct transformation of cartilage into 
bone was noted by Cornil and Coudray (’03) in the healing of 
fractures in the rabbit. They state that in most cases the car- 
tilage bordering the bone first ossifies along its edges while later 
the cartilage capsules themselves ossify, the cells being directly 
transformed into bone cells. 
It will be recalled that a portion of the distal end of the shaft 
is destroyed in the resorption process by which the old epiphysis 
is detached from the bone. This is: replaced by ossification of 
a part of the new cartilage in the manner just described. The 
further history of this process was not followed owing to lack of 
material in the advanced stages. 
7 Through an error, the leader from the letters M.c.n. does not point to this 
extension. 
