Cuar. VL] DIGESTION. 89 
pone, J determined to try whether it would act on enamel 
and dentine, but did not expect that it would succeed with 
so hard a substance as enamel. Dr. Klein gave mesome thin 
transverse slices of the canine tooth of a dog; small angular 
fragments of which were placed on four leaves; and these 
were examined each succeeding day at the same hour. The 
results are, I think, worth giving in detail. 
Eaperiment 1—May Ist, fragment placed on leaf; 8rd, tentacles 
but little inflected, so a little saliva was added; Gth, as the tentacles 
were not strongly inflected, the fragment was transferred to another 
leaf, which acted at first slowly, but by the 9th closely embraced it. 
On the 11th this second leaf began to re-expand; the fragment was 
manifestly softened, and Dr. Klein reports, “a great deal of enamch 
and the greater part of the dentine decalcified.” 
Experiment 2,—May 1st, fragment placed on leaf; 2nd, tentacles 
fairly well inflected, with much secretion on the disc, and remained so 
until the 7th, when the leaf re-expanded. The fragment was now 
transferred to a fresh leaf, which next day (8th) was inflected in the 
strongest manner, and thus remained until the 11th, when it re- 
expanded. Dr. Klein reports, “a great deal of enamel and the greater 
part of the dentine decalcified.” 
Experiment 3.—May 1st, fragment moistened with saliva and placect 
on a leaf, which remained well inflected until 5th, when it re-expanded. 
The enamel was not at all, and the dentine only slightly, softened. 
The fragment was now transferred to a fresh leaf, which next morning 
(6th) was strongly inflected, and remained so until the llth. The 
enamel and dentine both now somewhat softened; and Dr. Klein 
reports, “less than half the enamel, but the greater part of the dentine 
decalcified.” 
Experiment 4.—May I1st,a minute and thin bit of dentine, mois- 
tened with saliva, was placed on a leaf, which was soon inflected, and 
re-expanded on the 5th. The dentine had become as flexible as thin 
paper. It was then transferred to a fresh leaf, which next morning 
(6th) was strongly inflected, and reopened on the 10th. The decalci- 
tied dentine was now so tender that it was torn into shreds merely by 
the force of the re-expanding tentacles. 
From these experiments it appears that enamel is attacked 
by the secretion with more difficulty than dentine, as might 
have been expected from its extreme hardness; and both 
with more difficulty than ordinary bone. After the process 
of dissolution has once commenced, it is carried on with 
greater ease; this may be inferred from the leaves, to which 
the fragments were transferred, becoming in all four cases 
strongly inflected in the course of a single day ; whereas the 
