EXPLANATION OF THE PLATES. 



PLATE XXXVII. 



STRUCTURE OF TEETH. 



Fig. 1. Section of cementum magnified 670 diameters; in- 

 ternally, but really near the outer margin of the 

 cementum, some imperfectly developed bone cells 

 may be observed, each surrounded by a clear space, 

 having some resemblance to a cell wall ; externally, 

 and bordering upon the dentine, a closely aggre- 

 gated layer of still more imperfectly formed bone 

 cells are seen. 



2. Section of same traversed by tubes, continuations 



of those of the dentine. 670 diameters. 



3. Section of cementum, showing a number of small 



angular cells, and which may frequently be ob- 

 served in that portion of the cementum which lies 

 near to the dentine. 



4. Oblique section of healthy dentine, over the surface of 



which a fungus has developed itself. It is no un- 

 common circumstance to meet with sections thus 

 completely invested with a similar fungus ; I have 

 seen several such. 670 diameters. 



5. Oblique section of dentine, in which numerous bright 



globules, having a resemblance to oil globules, are 

 observed to be present. 350 diameters. 



6. Section of secondary dentine, and which also contains 



haversian canals. This drawing was made from a 

 preparation belonging to Mr. Tomes. 350 diameters. 



7. Transverse section of bicuspid tooth, showing the 



presence of an haversian canal in the cementum, 

 magnified with a lens only. This drawing has also 

 been made from an interesting preparation, the pro- 

 perty of Mr. Tomes. 



r 2 



