WOUNDS 



239 



whose length corresponds to the breadth of the wood-ring, and 

 a smaller one on the outside equal in length to the thickness of 

 the new bast. A cambium region persists between these two 

 portions till the dormant eye dies, when the bud-axis, which 

 is disposed at right angles to the main stem, ceases to grow 

 and is overgrown and enve- 

 loped by the advancing wood- 

 rings. 



Numerous bud-axes tra- 

 verse the wood of dicotyledo- 

 nous trees, exactly as is the 

 case with medullary rays. 

 Should these be stimulated 

 to form shoots (Fig. 136, c), 

 the latter produce their own 

 growth of wood, and both 

 they and their medulla form 

 an acute angle with the main 

 axis of the stem. 



In the case of some trees, 

 more particularly the beech, 

 a certain proportion of the 

 dormant eyes develop in a 

 peculiar manner after the ces- 

 sation of intermediary growth. 

 Concentric growth in thick- 

 ness of that portion of the 

 wood of the bud-axis which 

 is situated in the cortex and 

 bast gives rise to the familiar 

 wood-balls, or " spheroblasts " 

 (Fig. 137), which project from 

 the surface of the stem and 

 frequently exceed the size of 



rifle bullets. As they have no connection with the wood of 

 the stem, they may be detached by a slight pressure.* 



In the case of our conifers, almost all axillary buds are in the 



* [These " Spheroblasts " are very common on the old Beeches in Windsor 

 Park. Burnham Beeches, and elsewhere. ED.] 



FIG. 136. Longitudinal section of a 

 beech-stem, twelve years old. At a 

 two dormant axillary buds are shown 

 whose vascular bundles, b, stand at 

 right angles to the main axis. A third 

 dormant eye, c, had burst forth to 

 form a shoot two years previously. 

 A dwarf shoot, d, has been formed 

 by the unfolding of a bud when the 

 main shoot was a year old ; e, a shoot 

 that has been dead for four years. 

 Natural size. 



