210 MICROSCOPIC ANATOMY OF THE TEETH 



position in the text-books. Schweitzer in 1907 and 1909 (31) 

 published the results of his experiments on animals, and 

 was able to demonstrate the presence of lymph vessels in the 

 pulp ; this discovery was confirmed by Bartels in 1909 (1), 

 and also by Testut (32), who says, referring to Schweitzer, 

 ' This author has clearly demonstrated the presence of true 

 lymph vessels in the dental pulp'. The earlier observers, 

 as Korner and Halle, found that although they could not 

 find lymph vessels in the pulps of the animals experimented 



FIG. 127. Blood-vessels and nerves of the pulp. ( x 600. ) 



upon, single particles of the insoluble Prussian blue employed, 

 painted on the pulp at its upper end, were found as far as 

 the apex, but these results were not sufficiently convincing 

 even to establish the statement that although no lymph 

 vessels could be demonstrated, the pulp had the power of 

 resorption, and, as was suggested by Morgan, these particles 

 might be carried by wandering cells (20). 



Dewey and Noyes repeated the experiments of the previous 

 investigators, and made use of both the methods employed 

 by them : that of Korner, Starr, and Ollendorf of injecting 

 Prussian blue directly into the pulp, and Schweitzer's method 

 of injecting the lymph vessels in the gums. These authors 



