48 MICROSCOPIC ANATOMY OF THE TEETH 



(Ca lu Co.,(Po 4 ) 6 ), and that this salt forms in the finished 

 tissue 95-35 per cent, combined with magnesium phosphate 

 1-5 per cent., leaving an organic residue of 3-60 per cent. 



Hoppe-Seyler also considered that the enamel in the 

 infant contains a much larger amount of organic matter, 

 and this has been given by some authors as high as 14 per 

 cent. C. S. Tomes (18 c), however, justly points out that 

 such an analysis must be of a very uncertain nature, as the 

 difficulties to be met with in obtaining a sufficient amount 

 of the incomplete enamel at birth without contamination 

 with other substances would be almost insuperable. 



An analysis of the enamel of erupted or erupting young 

 growing teeth would be of the greatest value in deciding 

 the much-vexed question as to whether enamel undergoes 

 any changes after eruption resulting in further consolida- 

 tion. No such examination has, however, been recorded, 

 although there are very strong evidences that some such 

 change does take place in growing teeth. 



There have been considerable discrepancies in the analysis 

 of enamel given by different authors. Tomes accounts for 

 these discrepancies by the fact that the organic matter in 

 enamel had been estimated by the loss on ignition, but 

 that the water in intimate combination with the enamel 

 had not been accounted for, and he showed that in the 

 case of elephant's enamel as much as 4 per cent, of water 

 remained after the enamel had been dried for a long time 

 at a temperature of 300 F. He concludes that ' the total 

 loss on ignition is very nearly accounted for by the water 

 given off ', and what has hitherto been considered organic 

 matter is simply water in intimate combination with the 

 lime salts, and probably with the tribasic calcium phosphate, 

 as this substance retains in combination one or more equiva- 

 lents of water which it will not part with below a red heat. 

 Tomes 's conclusions from these experiments were that 

 enamel contains no organic matter. 



The most recent analysis of enamel is that given by Dr. 

 Lovatt Evans (10), who in a paper contributed to the Inter- 

 national Medical Congress in 1913 showed that the organic 

 matter in human enamel was between 1 and 2 per cent. 



Ground enamel, carefully separated from every other 



