T. C. WHITE ON THE SO-CALLED "NERVE OF THE TOOTH. 7 



minister to the nutrition and vitality of the tooth, since, when from 

 age or disease these tubes become consolidated, the fibrous structure 

 is re^Dlaced by one resembling horn, and, as a consequence, the 

 tooth dies, becomes loose and a source of painful irritation. If a 

 section of the dentine be made in a direction that shall cut across 

 the course of these tubes, each tube will present an irregular aper- 

 ture, and will be seen separated from its fellows by an almost equal 

 proportion of intertubular tissue. We need not now consider any 

 further the character of the dentine, as 1 shall have to recur to it 

 when speaking of its relation to tlie nerve ; but what I have laid 

 before you will enable you to understand the meaning of much of 

 the structure it is our especial object to examine in the central or 

 pulp cavity of a tooth. 



If we take a recently extracted healthy tooth and split it we 

 shall notice that the pulp cavity is occupied by a pinkish fleshy mass 

 about j of an incli long and -jV^li of an inch wide at its upper and 

 thickest part ; it partakes somewhat of the external shape of the 

 tooth, being wide in the upper part, and tapering towards the tooth : 

 this, then, is what is popularly called the " nerve." In physiological 

 parlance it is termed the pulp. The basis of this pulp is composed 

 of areolar tissue, whose interstices are filled with a homogeneous 

 plasma. * 



A microscopical examination of its exterior will reveal an infinite 

 number of small points, giving to it an appearance not much unlike 

 the cross section of the tubes of the dentine, both as regards size 

 and distribution. Having noticed this much, recourse must be had 

 to compression before we can readily make out the arrangements of 

 its internal structure. Before proceeding to flatten it by pressure 

 it may be withdrawn from its cavity, and allowed to soak in the 

 ammoniacal solution of carmine, recommended by our President in 

 his book " How to Work with the Microscope ;" let it remain in it 

 twenty-four hours, wash away the carmine fluid, and transfer it to 

 glycerine for a few hours ; then put it under gentle, gradual pressure 

 for some few hours more, when it will be rendered sufiiciently thin 

 to be easily examined by a \ oi an inch objective or higher 

 powers. 



Commencing our examination at that part of the pulp nearest 

 the apex of the root, we shall notice it entering the foramen of 

 the fang as a fine thread, which though so fine nevertheless con- 

 veys the nerve and the artery into the pulp, and gives exit to the 



