230 MICROSCOPIC ANATOMY OF THE TEETH 



sections we think there can be no doubt, and in properly 

 prepared Weil sections there is no evidence of any stretching 

 of the pulp tissue or disturbance of any of the tissues ; in 

 fact, they are seen in their definite relations to one another 

 probably more perfectly than by any other process (22 d). 

 In 1908 Mr. Law (17) read a paper before the Odonto- 

 logical section of the Royal Society of Medicine in which 

 he described his investigations with Bethe's methylene blue 

 process. He found large fibres running up to the dentine 

 in the pulp, but the few sections made use of did not show 

 any connexion with nerve fibres in the pulp, and it could 

 not therefore be clearly demonstrated that they were nerve 

 fibres. He stated that in these preparations he could find 

 no trace of the deep plexus, or plexus of Raschkow. 



Dr. Dentz of Utrecht found in some sections of developing 

 human teeth a row of pear-shaped bodies near the outer 

 margin of the dentine. These bodies had very much the 

 appearance of nerve-end organs ; they each contained 

 several large bodies resembling nuclei, and the area of den- 

 tine surrounding the outer club-shaped end showed a certain 

 amount of modified dentinal tissue with few or no tubes. 

 These bodies apparently represent some abnormality in 

 development, as being of very large size (^th inch), they 

 must have been conspicuous in other preparations had they 

 been constantly present in deciduous teeth. No nerve fibres 

 could be traced into them, and it is difficult to account for 

 their occurrence in these preparations. These bodies are 

 shown in figs. 139 and 140 under a high and low power, and 

 were photographed from the specimen kindly lent to the 

 author by Dr. Dentz. 



Persistent Pulps. Persistent pulps are found in teeth 

 which are subjected to constant and severe attrition, as the 

 incisors of Rodents. The pulp is not completely enclosed 

 within a bony cavity as in the majority of teeth, but remains 

 open at the base, and is continually growing during the life 

 of the animal, new hard tissue being deposited by the 

 formative cells of the pulp as the tip of the tooth becomes 

 worn down in use. The nerve trunk to the pulp runs 

 backward beneath the tooth and then bends abruptly and 

 enters the pulp, showing that the tooth is continually 



