Ouar. VI. DIGESTION. 107 
Experiment 1.—May Ist, fragment placed on leaf; 3rd, ten- 
tacles but little inflected, so a little saliva was added; 6th, 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 enamel and the greater 
part of the dentine decalcified.” 
Experiment 2.—May 1st, fragment placed on leaf; 2nd, ten- 
tacles 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, “agreat 
deal of enamel and the greater part of the dentine decalcified.” 
Experiment 3.—May Ist, fragment moistened with saliva and 
placed 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 11th. 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 1st, a minute and thin bit of dentine, 
moistened 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 decalcified 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 ex- 
treme 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 first set of leaves acted much less quickly and 
