■ Teeth of the Guinea-pig, produced by a Scorbutic Diet. 507 



all the appearances of the changes of senility. A great number of longi- 

 tudinal and transverse sections suitable for microscopic examination were 

 obtained. The revelations offered by these sections are of a particularly 

 interesting nature. It would require too much space to describe all the 

 sections of teeth examined and we, therefore, consider it more appropriate 

 to sum up the changes that take place. 



Figs. 1 and 2 (Plate 13) are of a normal tooth and give one the opportunity 

 of studying the histology of the dental pulp in its normal relationship to 

 dentine. The enamel is not quite so heavy as in the natural tooth, on 

 account of the decalcifying process which has reduced it to about half its 

 thickness, but it gives one an excellent example of the typical relationship 

 to the dentine of the blood vessels, the fine cellular tissue, and odontoblastic 

 cells when in a normal condition. Note the fine-cut lines of the dentine and 

 odontoblastic cells as compared with figs. 3 and 4. 



Figs. 3 and 4. — It is obvious that the term " fibrosis " or fibroid degenera- 

 tion, is the only one which can with certainty be applied to this particular 

 form. There is no doubt that it is a specimen of degeneration, and it is 

 equally easy to eliminate those other degenerative varieties, such as mucous, 

 calcareous, or fatty, which animal tissues may undergo. 



The present instance affords an opportunity of examining certain structural 

 metamorphoses in the pulp, which are believed not to be dependent on any 

 inflammatory condition, but simply attendant on and produced by altered 

 metabolism or constitutional changes due to diet. This affection seems to 

 have been unknown or overlooked by the pathologists both in Europe and 

 America. Minute descriptions have been published on pulp nodules, 

 calcareous pulps, and elaborate work ou ulcers and tumours connected there- 

 with. In no case does one find the condition as depicted in figs. 3 and 4 

 brought about by a dietetic experiment. 



It is evident in this picture that in complete pulpar fibrosis no cellular 

 elements of any description occur. It is clear at once and it is an 

 important fact that no trace of cellular organisation, no trace of cell nuclei, 

 no trace of interstitial cement substances can be found anywhere. Nerves, 

 cells, blood vessels and odontoblasts have all shared the process of fibrification 

 and are no longer recognisable. The fine cellular connective tissue which ia 

 but a loose mass of network in the normal state, has either become grossly 

 hypertrophied or quite obliterated, and its place taken by a new firm, fibrous 

 structure, devoid of cells, nuclei, or any regular arrangement of constituted 

 parts, rigs. 3 and 4 show an advanced state of scurvy. The irregular osteoid con- 

 dition of the dentine is well marked and the different refractive appearance of 

 the dentine is probably due to the heemorrhagic condition of the dentinal fibrils. 



