PHENOMENA OF PLANT-LIFE. 95 



FIG. 34 represents the same elements of the new bark formed on 

 the place girdled, July twenty-first, the periderm being 

 of a reddish brown color. 



FIG. 35 is a view of the section of a weeping willow tree, to illustrate 

 the mode of growth in trees from which the bark has been 

 loosened by freezing. 



A is sap-wood formed on the inside of the bark and discon- 

 nected from the wood of the trunk. 



B is new wood and periderm formed on the old wood, to 

 which a portion of the cambium cells remained attached 

 when the old bark was torn off by the frost. 

 C, roots developed from the uninjured stem under the old 

 disrupted bark, and extending to the earth, a distance 

 of more than fifteen inches. 



FIG. 36 exhibits a specimen of a pendant weeping willow branch, which 

 was girdled in June last The growth was on the lower side 

 of the girdled place, showing that the flow of the elaborated 

 sap is not necessarily downward, but roo^-ward. 



FIG. 37 is a view of a pistillate plant of mistletoe, with evergreen 

 coriaceous leaves and white berries, growing on the limb of 

 an oak. 



A represents the parasitic roots of the mistletoe in the sap- 

 wood of the oak. As the oak was dead beyond the large 

 cluster of the parasite, it seems that it was injured by the 

 loss of its sap. 

 FIG. 38 illustrates the natural grafting of two trunks of white pine. 



A is the smaller trunk, a branch of which is seen to grow 

 through the wood of the larger one. The union of wood 

 is perfect, and the elaborated sap from B has flowed 

 so freely over the connecting branch, that A is larger 

 below, and B larger above the place of junction. 

 C is the knot in the heart of B, formed of the base of the limb, 

 in the axil of which D, the connecting branch, became 

 fastened in the beginning of the operation. 

 FIG. 39 shows the grafted roots of a white pine stump, the points of 



union being very numerous. 



FIG. 40 exhibits a section of a small white birch tree, one of whose- 

 branches has become grafted to it in consequence of being 

 caught in the axil of a branch above. 



FIG. 41 represents a section of the trunk of a small aspen, around which 

 a vine of bitter-sweet has twined so closely as to prevent the 

 root-ward flow of elaborated sap. The growth therefore 

 follows the bitter-sweet in a spiral direction. 



FIG. 42 shows a longitudinal section of the preceding specimen. The 

 wood is seen to have formed from above so as to cover the 

 vine, while immediately below it there has been no growth 

 whatever. 



FIG. 43 exhibits the dead wood of an apple tree limb, which was depos- 

 ited so that the fibres run in a spiral direction. 



