14 
Proceedings of Royal Society of Edinlurgh. 
SESS. 
On the Madder-Staining of Dentine. By W. Gr. Aitchison 
Robertson, M.D., D.Sc., F.R.C.P.E., Physiological Labor- 
atory, University of Edinburgh. (With a Plate.) 
(Read December 19, 1892.) 
While working at the histology of the tooth, it occurred to me 
that some light might be thrown on the vexed question as to. the 
manner in which dentine grows, by observing what parts of a tooth 
are stained when an animal is fed on madder mixed with its food. 
In order to investigate this I examined the persistently growing 
teeth in three young rabbits, all of the same litter, which had been 
fed on madder {Ruhia tinctorum) for two weeks. The first rabbit 
was killed immediately after being thus fed ; the second was killed 
after feeding for two weeks on ordinary diet subsequent to the 
madder food ; while the third was killed three weeks after feeding 
with madder had been discontinued. 
I. Young Rabbit killed after Feeding for two weeks 
ON Food with Madder. 
(A.) Lower Incisor. Length, 14 mm.; greatest breadth, 2 mm. 
(1) External appearance. The greater part of each tooth is 
stained a beautiful light lake colour. This grows lighter, and fades 
off entirely towards the free extremity of the tooth, leaving the 
upper quarter quite unstained and white. The staining is most 
marked towards the root and in the natural furrows (fig. 1, a). 
if) On section. The upper third of the tooth is almost quite 
unstained, except at the centre in the position of the obliterated 
pulp-cavity. In this position the staining extends up to the free 
masticatory surface of the tooth as a narrow band on each side of 
the dark line representing the obliterated pulp-cavity. Although 
the whole of the lower two-thirds is stained, the dentine in imme- 
diate contact with the pulp is stained more deeply than that situated 
further out (fig. 1, h). 
