BONE. 303 



GKOWTH AND DEVELOPMENT OF BONE. 



Growth of Bone. The situations in which the chief 

 increase of bone occurs are commonly stated to have been 

 accurately determined by means of the different madder 

 experiments instituted by numerous observers. 



If an animal be fed for a short time with the root of 

 madder, its bones will become tinged with the colouring 

 matter of that plant, between which and the phosphate of 

 lime of the bone a great affinity exists. 



On a close examination of sections of a growing long bone 

 it will be observed, however, that the tissue of the bone is 

 not uniformly coloured, but that in a transverse cutting the 

 colour is principally situated in the outer part. The same 

 fact is shown also in longitudinal sections, which, however, 

 if they embrace the entire length of the bone, will also be 

 observed to be tinged with the colouring matter towards 

 either extremity. 



Again, if a magnifying glass be applied to a thin trans- 

 verse section of the growing bone of an animal fed upon 

 madder, each Haversian canal will be seen to be surrounded 

 by its ring of colour. For this beautiful illustration of the 

 effects of madder we are indebted to Mr. Tomes. (Plate 

 XXXIII. fig. 6.) 



These several observations have been presumed to prove 

 that bones increase in length principally by additions of new 

 matter to their extremities, and in breadth by the deposition 

 of new lamina? of bone on their outer surface, as well as by 

 the formation of fresh lamellae in each Haversian canal, which 

 last grow and expand in size simultaneously with the Iamina3 

 placed external to them after their first formation. 



Now, although it is very probable that bones increase 

 in diameter to a great extent by the addition of new matter 

 on the external surface, and although it is quite certain that 

 they become elongated by the formation of bony matter at 

 their extremities, it appears to be most clear that we are not 

 justified in coming to any such conclusion from the results of 

 the experiments with madder. All that these celebrated 



