44 ON GROWTH AND EXTENSION IN THE VEGETABLE KINGDOM, 



graft of Prunus nigra on a stock of the same species, we 

 observe the transition of the outer wood of the stock into that 

 of the scion without any interruption ; then the inner wood of 

 the scion partly dead an'! hecome brown ; then the central wood 

 of the stock, which has formed no connection whatever with 

 the scion ; and, lastly, the thickened wood of the scion, which 

 begins to grow over the stock. I find it to be the same in all the 

 many grafted stems and branches wliicli have succeeded and 

 grown, wliich I owe to the kindness of the university gardener, 

 M. Sauer. The interior of the stock has always suffered, al- 

 though less in old than in young stocks, and has turned brown ; 

 and a stem of Fraxinus pendula, which had been grafted by cleft- 

 grafting on two opposite f-ides, showed in the centre a portion of 

 the stock not in the least connected with the grafted brancli, but 

 enclosed * on every side by the outer wood of the graft. But 

 the specimen is sufficiently instructive to deserve further notice. 

 It had been sawed off from the stem immediately below the graft 

 and also close above it ; below, it is nearly cylindrical, and about 

 3 inches in diameter ; above, it is enlarged and ellipsoidal, being 

 5t inches broad in one direction, and 3 in the other. It was 

 sawed through longitudinally, and showed the original stock very 

 plainly, not in the centre, but on the right-hand side, close under 

 the transverse cut. Tliis stock is half an inch in diameter, is 

 cut clean off at the upper end, and separated from the grafted 

 branch by a fissure with a brown border ; laterally, tlie fissure 

 shows itself slightly at the upper end, but soon ceases ; in its 

 place a brown line stretching downwards continues to mark out 

 the original stock. One of the grafted branches on the left has 

 in its transverse section the form of an ellipsis of 3 inches by 2, 

 with 4 annual rings of wood ; the other branch on the right has 

 in its transverse section a nearly circular form of about an inch 

 in diameter, with the same number of 4 annual rings, but much 

 smaller, the broader inner ones arching over the stock. Between 

 these branches the space has been filled up with a globular-shaped 

 piece of wood, consisting of several layers arched invertedly. On 

 the left they run parallel to the inclined layers of the grafted 

 branch, but on the right they penetrate irregularly into the 

 layers of the grafted branch. Round these layers are five layers 

 of varying thickness, under a bark a line thick, which encircles 

 the whole. This is therefore an appropriate structure, partly for 

 filling up all vacant spaces, partly to unite the whole into one 



* I borrow this expression from M. Goeppert, that the trunk of a felled 

 ti-ee becomes covered with new wood — enclosed by it, when it receives fresh 

 nutriment from a naturally engrafted root-branch of some adjoining tree. 

 Such fortuitous grafting is not uncommon. I have a carrot of which the 

 pointed end of the tap-root has grafted itself on another carrot. 



