256 



GROWTH OF BONE. 



Fig. 112. 



Fig. 113. 



Ossifying femur. 



Ossifying cartilage, magnified 50 diameters. 



Fig. 113, femur of a child a fortnight old, natu- 

 ral size : #, substantia compacta of the shaft ; b, 

 medullary cavity ; c, substantia spongiosa of the 

 shaft ; d, cartilaginous epiphysis, with vascular ca- 

 nals ; e, osseous nucleus in the inferior epiphysis. 

 (Kolliker.) 



When silver rings are placed upon the shaft of 

 Growth of a growing bone at a measured dis- 

 siiverrings^nd tance > subsequent examination shows 

 madder. that that distance still remains the 



same, though the bone may have become much 

 longer. If such a ring be permitted to remain a sufficient period of time, 

 it will eventually be found in the interior of the bone. When madder 

 is mixed with the food of pigs, its coloring matter so unites with the 

 phosphate of lime of their bones as to impart to them a red tint. If the 

 animal submitted to the experiment be very young, the whole skeleton 

 may be tinged in a single day, a more close examination showing, how- 

 ever, as might be expected, that the portion most completely acted upon 

 is that nearest to the vascular surface. In older animals the coloring 

 goes on more slowly ; the portion which shows the effect most striking- 

 ly is between the shaft and extremities, more particularly upon the sur- 

 face. If the madder be given, periodically and then withheld, alternate 

 layers of a red and white appearance are produced. 



From these experiments, it may be inferred that the growth of a bone 

 Conclusions is not uniform in all parts. Young bones grow chiefly toward 

 such" ex f peri- ^ e extremities ; nor is the growth cumulative, the parts al- 

 ments. ready deposited being ever after preserved ; for, if that were 



the case, it would not be possible for a ring placed in such a manner as 

 has been described to find its way into the medullary canal. For that to 



