642 THE TEETH. 



small, oblong nuclei at their points of intersection. The meshes either look 

 pale and finely granular throughout, or contain a bright yellowish, either 

 homogeneous or granular, body of the size of a nucleus. The number of the 

 latter formations greatly varies in different pulps. Where bundles of a fibrous 

 tissue traverse the reticulum, the latter blend with the former. 



In longitudinal sections the medullated nerves show the well-known fluted 

 double contour the sheath of Schwann. It exhibits delicate oblong or 

 spindle-shaped nuclei. External to this we observe a delicate layer of fibrous 

 connective tissue, the "internal perineurium." In cross-sections of the nerve- 

 bundles more or less circular groups of medullated nerve-fibers are seen, each 

 of which in its center exhibits the axis-cylinder in the shape of a roundish, 

 glistening dot. Not infrequently capillary and arterial blood-vessels are met 

 with between the nerve-fibers. 



As to lymphatics of the pulp, I can say that in some specimens I have seen 

 branches of vessels of the size of veins without an adveiititial coat, being 

 composed of large, flat, and slightly protruding endothelia. 



At the periphery of the pulp the delicate reticulum constituting the pulp- 

 tissue is very dense ; here we meet with narrow capillary blood-vessels only. 

 The outer surface of this layer is often uniformly granular, and bounded by 

 radiating rows of shining corpuscles. 



In chromic acid specimens stained with carmine, or, still better, in those 

 treated with chloride of gold, high amplifications (1000 to 1200 diameters) 

 reveal an extremely minute reticular structure pervading all formations of 

 the pulp. Starting from the center of a mesh of the myxomatous tissue we see 

 a nucleus, either homogeneous and apparently destitute of structure, or of the 

 appearance of a vesicle with a distinct bright wall. Inside the hollow nucleus 

 we see a varying number of bright granules interconnected with each other, as 

 well as with the inclosing wall, by means of delicate filaments. Such filaments 

 connect also the nucleus with the extremely delicate grayish reticulum in the 

 light basis-substance contained in the mesh. This reticulum in the basis-sub- 

 stance is recognizable even though the central nucleus be absent. The 

 fibrous or bioplasson net-work which incloses the mesh-spaces also shows a 

 delicate reticulum in connection with the nuclei at the points of intersection. 



The formations at the periphery of the dental pulp, termed odontoblasts, 

 under high amplifications exhibit the following : Elongated fields, somewhat 

 resembling epithelia, border the pulp in a radiating direction. Each field may 

 appear in the shape of a granular bioplasson, or in that of basis-substance, in 

 either of which oblong nuclei are imbedded in varying numbers. The nuclei 

 exhibit coarse granules and a dense reticulum of living matter. The bioplas- 

 son bodies are separated from each other by delicate light rims, in which we 

 see sometimes broad, sometimes delicate, transverse fibrillsB in connection 

 with the reticulum of the neighboring formations. The bioplasson bodies or 

 odontoblasts furnish the matrix for the basis-substance of the dentine, while 

 the dentinal fibers, being formations of living matter, originate between the 

 odontoblasts. 



The medullated nerve-fibers, upon approaching the periphery of the pulp, 

 become destitute of their myeline sheath, and, now being bare axis-cylinders, 

 branch into numerous extremely delicate beaded fibrillee the "axis fibrillge." 

 These ferminate, with knob-like extremities, in the granular layer beneath 

 the odontoblasts, or they penetrate the light rims between the rows of the 

 odontoblasts, and are connected with the latter by means of delicate conical 



