2i8 TIMBER AND SOME OF ITS DISEASES, [chap. 



interesting histological questions connected with this 

 callus-formation, or with the mechanical relations of 



Co C<5 



Fig. 32. — The same in longitudinal section : lettering as before. Six new layers of 

 wood have been developed, and the cut end of the branch was completely 

 occluded before the last three were formed — i.e. at the end of 1885. After thai 

 the cambium became once more continuous round the whole stem, and, beyond a 

 slight protuberance over the occluded wound and the ragged edges of the dead 

 corky outer layers, B^ there are no signs of a breach. 



the various parts one to another. It is sufficient for 

 our present object to point out that this process of 

 covering up, or occlusion^ as I propose to term it. 



