ON THE SO-CALLED {< NERVE ” OF THE TOOTH. 365 
ning side by side for some distance., and when you expect to 
see a loop the ends are found separated; this may probably 
arise by the pressure used to render the pulp thin enough 
for observation. Some specimens, again, show a very appa¬ 
rent looping of the fibres, but the loops extend round the cir¬ 
cumference towards the end of the pulp, they are so large; 
but in no case have I met with fibres that would lead us to 
suppose that were they small enough to enter the tubuli that 
they do so. How, then, are we to account for the painful 
sensation experienced in cutting into live dentine, unless we 
suppose that a connection of some kind exists between the 
tubuli and the fibres of the nerve ? The only theory that 
can be suggested is that the dentinal fibre contained in a tube 
of the dentine passes out through its odontoblast, and then, 
becoming fused with the nerve, conveys the sensation to the 
brain, and we are conscious of the irritation. 
I have not found it possible to see this connection between 
the odontoblast and the nerve fibres, because the reagents 
usually employed to render nerves visible, dissolve away the 
odontoblasts ; neither have I, by means of thin sections, been 
more fortunate, as the proximal caudal appendage of the 
odontoblastJs too transparent and too minute to admit of 
demonstration, except, perhaps, by the employment of new 
reagents; in specimens of the pulp, that after staining with 
carmine have been teased out with needles, the isolated fibres 
have had, besides their own coloured nuclei, coloured odonto¬ 
blasts, with this internal caudal appendage fused into their 
outer parts. Such may be the general mode of their connec¬ 
tion, but I am not clear on that point. Such, then, are a 
few of the principal elements met with in a microscopical ex¬ 
amination of what is popularly termed the ec nerve” of a tooth, 
but in case any member present may feel inclined to work 
out these details for himself, it may be as w r ell to append a 
few remarks relative to the plans of investigation, attended 
by the best results. The teeth employed have been tem¬ 
porary teeth, removed in a healthy condition, to make room 
for the advancing permanent set, any others being unsuitable 
from disease. It is necessary to exercise great care in ex¬ 
tracting the pulp from them, as the bone dust from the tooth 
and impurities of various kinds cling most tenaciously to the 
odontoblasts, and not only obscure the view of the delicate 
details, but look unpleasant and slovenly. The plan found 
to answer best is to file a longitudinal groove round the 
tooth ; then, having washed away all the debris very tho¬ 
roughly, split the tooth with a pair of wire nippers, when it 
will come clearly in two and expose the pulp for its whole 
