300 james crawford watt. 



Results of Examination of Bone. 



Both bright and dark field illumination were employed and 

 specimens of bone, when thin, were quite transparent and easily 

 examined. In bone that is well formed, whether from adult, or 

 young individual, or foetus, the appearances are similar. The bone 

 cells and all their processes in the canaliculi are easily followed and 

 appear as Bast has described them. The matrix round about them 

 is homogeneous, transparent, and almost glassy in appearance, and 

 gives jio indication (Fig. 37) of being formed of separate parti- 

 cles. If it was originally formed in such a manner, there has been 

 complete fusion, so that there is no evidence of a precipitation. In 

 fact, the whole appearance bears out the statements of text-books 

 of histology that, although two thirds of the bony matrix is com- 

 posed of inorganic salts, they are so intimately blended with the 

 organic material that there is no visible evidence of their presence. 



In the case of growing long bones, such as those of the limbs, 

 sections were taken across the shaft to include the newly formed 

 growing periphery just under the periosteum, and also sections in 

 the length of the bone to include the end of the diaphysis, the 

 epiphyseal plate of cartilage, and the bony epiphysis. These sec- 

 tions, however, were disappointing, as even at the transitional areas 

 any tissue that could be identified as bony matrix appeared homo- 

 geneous, so that no evidence of precipitation could be obtained here. 



In the case of the developing diaphysis of the long bones of the 

 limbs in human foetuses, however, there were definite, discrete 

 particles to be seen. In Ouain's Anatomy there is a fine de- 

 scription by Schafer of the appearances of developing bone with 

 which my findings entirely agree. Just ahead of the advancing 

 bone of the diaphysis is an area of change, where the tissue is no 

 longer cartilage, but is not yet true bone. Here we find definite 

 fibres (Fig. 38) like those of white fibrous tissue, and known as 

 Sharpey's fibres, extending from the bony material forward into 

 the cartilage, and in these fibres in the narrow area immediately in 

 advance of the true bone are numerous very fine granules which 

 appear similar to the material of the matrix in well-formed bone 

 and so are evidently the bone salts. They are crowded in the 

 fibres just ahead of the actual bone, and in the bone itself we find 



