CHAP. VI. DIGESTION. 107 



Experiment 1. May 1st, fragment placed on leaf ; 3rd, ten- 

 tacles 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 llth 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 llth, 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 

 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 (Gth) 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 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 (Gth) 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 ia 

 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 aud 



