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Show 42 IIABITS OF WORMS. OnAP. r. udat1on of the secretion through the epidermis into the cells. The secretion with which worms moisten leaves likewise acts on the starch granules within the cells. My son examined some leaves of the ash and many of the lime, which had tall en off the trees and had heen partly dragged into worm-burrows. It is known that with fallen leaves the starchgrains are preserved in the guard-cells of the stomata. Now in several cases the starch bad partially or wholly disappeared f~om these cells, in the parts which had been m01stened by the secretion; while they were still well preserved in the other parts of the same leaves. Sometimes the starch was dissolved out of only one of the two guard-cells. The nucleus in one case had disappeared, together with the starch-granules. The mere burying of lime-leaves in damp earth for nine days did not cause the destruction of the starchgranules. On the other hand, the immersion of fresh lime and cherry leaves for eighteen hours in artificial pancreatic fluid, led to the dissolution of the starch-granules in the guardcel1s as well as in the other cells. CHAP, I. CALCIFEROUS GLANDS. 43 From the secretion with which the leaves are moistened being alkaline, and from its acting both on the starch-granules and on the protoplasmic contents of the cells, we may infer that it resembles in nature not saliva,* but pancreatic secretion ; and we know from Fredericq that a secretion of this kind is found in the intestines of worms. As the leaves which are dragged into the burrows are often dry and shrivelled, it is indispensable for their disintegration by the unarmed mouths of worms that they should first be moistened and softened ; and fresh leaves.' ~owever soft and tender they may be, are similarly treated, probably from habit. The result is that they are partially digested before they are taken into the alimentary canal. I am not aware of any other case of extra-stomachal digestion having been reco. rded .. The boa-constrictor bathes its prey :V1th sah va, but this is solely for lubricating It. P.erbaps the nearest analogy may be found In such plants as Drosera and Dionrea · for here animal matter is digested and con~ •. Claparede doubts whether saliva is secreted by worms : see ' Zmtschrift ftir wissenscbaft. Zoologic,' B. xix. 1869, p. 601. |