TRANSFORMATION OF CARTILAGE. 457 



or less set free in a softer basis-substance. Simultane- 

 ously with the occurrence of this softening the chemical 

 reaction of this tissue also becomes altered, and we 

 always obtain the distinct reaction of mucin. At the 

 same time divisions begin to take place, and this not in 

 the same way as previously, when the cellular elements 

 at once separated into two new analogous cells (hyper- 

 plasia), but rather in such a way, that a number of little 

 nuclei arise in them (physiological heteroplasia). Sub- 

 sequently, in proportion as this process of transforma- 

 tion reaches a higher and higher pitch, and fresh por- 

 tions of the intercellular substance are continually being 

 converted into this more homogeneous and soft matter, 

 the cells generally divide, and we obtain a number of 

 smaller ones, which are very minute in comparison to 

 the large cartilage-cells, from which they proceeded, and 

 contain either a single nucleus with a nucleolus, or 

 sometimes also, like pus-corpuscles, several nuclei. 

 Thus gradually arises a tissue extremely rich in cells, 

 the young, red, medullary tissue, as we generally find it 

 in the marrow of new-born infants. If the process 

 stops here, the size of the transformed spot indicates 

 at the same time the extent of the subsequent medul- 

 lary space. Subsequently, these little cells may take up 

 fat, and then it appears, first in small granules, but by 

 degrees in large drops, and at last to such an extent that 

 the cells are entirely filled with them. Thereby the 

 original medullary tissue is transformed into adipose 

 tissue ; the fat, however, is always contained in the 

 interior of the marrow-cells, as it is in the cells of the 

 panniculus adiposis. But this yellow, fatty marrow does 

 not occur in all bones. In the bodies of the vertebrae 

 we almost always find the small cells. In the long 

 bones of the adult the fatty marrow alwaj^s occurs 

 normally, but in pathological conditions it may very 



