104 TOMES, ON THE DENTAL TISSUES. 



the very young subject, deprived of their salts, detached from 

 each other, and floating about in the fluid in wliich the section 

 is preserved. 



The figures illustrating these forms were drawn from 

 specimens which retain the conditions figured. The appear- 

 ances described do not admit of dispute ; but the interpre- 

 tation of their origin may perhaps be differently given by 

 observers who do not agree upon the manner in which the 

 enamel is developed. I do not propose to enter upon the 

 question of development ; but shall for the present leave the 

 subject, after stating the varying conditions of enamel as it is 

 found in human teeth. 



In well-formed teeth, although the cell-like markings in the 

 enamel are not by any means as distinct as in teeth in the 

 condition I have described ; yet having first examined the 

 latter, but little difficulty will be experienced in recognising 

 here and there faint indications of a similar structure, espe- 

 cially if the light be well managed. The more perfect the 

 development of the tooth, the more transparent and free from 

 markings will be the enamel, when seen as a microscopic 

 object ; and the less perfect the more distant will be the 

 columns of granular cell-fibres. 



Examples may readily be found in v/hich the union be- 

 tween the enamel fibres is so defective that the tissue readily 

 breaks down ; a condition rendering it very difficult to grind 

 it sufficiently thin for microscopic examination. When ob- 

 tained, however, such specimens are very instructive, as they 

 show distinctly the individual fibres and their contents, which 

 in the most highly-developed tissue are so perfectly fused 

 together, that the stroui^ly-marked distinction of parts, which 

 is so obvious in the one, is almost entirely lost in the other. 



From what has been stated it will be seen that my view of 

 the structure of enamel is as follows : — 



The enamel fibres are composed of a sheath containing a 

 series of cells or masses ; that in perfectly-developed enamel, 

 the cells or masses and sheaths are so blended that but sliglit 

 distinction of parts remains, but that in less perfectly de- 

 veloped tissue the component parts remain visible. 



{Tu he continued.') 



