of a sheep with weak hydrochloric acid; and seven minute fragments of the fibrous basis were placed on so many leaves, four of the fragments being first damped with saliva to aid prompt inflection.  All seven leaves became inflected, but only very moderately, in the course of a day. [page 109] They quickly began to re-expand; five of them on the second day, and the other two on the third day.  On all seven leaves the fibrous tissue was converted into perfectly transparent, viscid, more or less liquefied little masses.  In the middle, however, of one, my son saw under a high power a few corpuscles, with traces of fibrillation in the surrounding transparent matter.  From these facts it is clear that the leaves are very little excited by the fibrous basis of bone, but that the secretion easily and quickly liquefies it, if thoroughly decalcified.  The glands which had remained in contact for two or three days with the viscid masses were not discoloured, and apparently had absorbed little of the liquefied tissue, or had been little affected by it.

Phosphate of Lime.—­As we have seen that the tentacles of the first set of leaves remained clasped for nine or ten days over minute fragments of bone, and the tentacles of the second set for six or seven days over the same fragments, I was led to suppose that it was the phosphate of lime, and not any included animal matter, which caused such long continued inflection.  It is at least certain from what has just been shown that this cannot have been due to the presence of the fibrous basis.  With enamel and dentine (the former of which contains only 4 per cent. of organic matter) the tentacles of two successive sets of leaves remained inflected altogether for eleven days.  In order to test my belief in the potency of phosphate of lime, I procured some from Prof.  Frankland absolutely free of animal matter and of any acid.  A small quantity moistened with water was placed on the discs of two leaves.  One of these was only slightly affected; the other remained closely inflected for ten days, when a few of the tentacles began to [page 110] re-expand, the rest being much injured or killed.  I repeated the experiment, but moistened the phosphate with saliva to insure prompt inflection; one leaf remained inflected for six days (the little saliva used would not have acted for nearly so long a time) and then died; the other leaf tried to re-expand on the sixth day, but after nine days failed to do so, and likewise died.  Although the quantity of phosphate given to the above four leaves was extremely small, much was left in every case undissolved.  A larger quantity wetted with water was next placed on the discs of three leaves; and these became most strongly inflected in the course of 24 hrs.  They never re-expanded; on the fourth day they looked sickly, and on the sixth were almost dead.  Large drops of not very viscid fluid hung from their edges during the six days.  This fluid was tested each day with litmus paper, but never coloured