NATURE BARRICADING DISEASE. 139 



of the tooth ; if from without, it will arise from the 

 periodontal membrane where it meets the gum." 



Dr. John Tomes thus describes the conservative ac- 

 tion of nature (barricading disease, as it were) when a 

 tooth is affected with caries (" Dental Physiology and 

 Surgery"): 



" When a portion of dentine has become dead, it is 

 circumscribed by the consolidation of the adjacent liv- 

 ing tissue. The tubes, becoming filled up, are ren- 

 dered solid, and the circulation is cut off from the dead 

 mass. This consolidation does not go on gradually 

 from without inward, keeping in advance of the decay, 

 but occurs at intervals. It seems that successive por- 

 tions of dentine lose their vitality, and that the contig- 

 uous living portions become consolidated." 



Prof. M. H. Bouley and Surgeon P. B. Ferguson are 

 the joint authors of a memoir on horses' teeth, which 

 fills thirty or more pages of " The Veterinarian " for 

 1844. The substance of the part which relates to the 

 pathology and dentistry of the teeth is as follows : * 



" 1. Anomalies in the Number of the Teeth. Some- 

 times, but very rarely, we meet with supernumerary 

 grinders in the horse. The anomaly may be caused 

 by the persistence of the temporary teeth, the develop- 

 ment of abnormal teeth on one or both sides of the 

 arcades (rows of teeth), and the cutting of a greater 



* The phraseology of Messrs. Bouley and Ferguson's memoir 

 has been more or less changed and the matter somewhat con- 

 densed and rearranged. The surgeons' golden ideas deserve to 

 be set forth in clearer and more forcible language than they re- 

 ceive at their own hands, and it is believed that some improve- 

 ment has been made. 



