CHAP. V L DIGESTION. 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 lique- 

 fied 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 trans- 

 parent 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 lique- 

 fies it, if thoroughly decalcified. The glands which 

 had remained in contact for two or three days with 

 the viscid masses were not discoloured, and appa- 

 rently had absorbed little of the liquefied tissue, 

 or had been little affected by it. 



Phosphate of Lime. As we have seen that the ten- 

 tacles 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 in- 

 flection. 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. Frank- 

 land 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 



