8 
A. V. Duthte. 
years old (Plate II, Fig. 1). The wood was morticed out to the 
depth of about 13 cm., and the peg, which is 6^ cm. thick and 22 
cm. long, was driven in, leaving about 13 cm. projecting from the 
wound. This projecting portion was completely covered over in 38 
years. The effect of the injury is observable in the widening of the 
annual rings to a lateral distance of over 5 cm. from the wound. 
The average breadth of the rings formed immediately before the 
injury is under 3 mm., the greatest breadth (12 mm.) is reached in 
the second year after wounding. From this point the breadth of 
the successively formed rings of wood decreases, until after 9 years 
from the injury the breadth of about 3 mm. is once more attained. 
As the callus lips arch over the jagged end of the deal peg they 
broaden once more (Fig. 1), pushing into every erevice and coming 
into close contact with its irregular surface. A considerable amount 
of cortical tissue was formed in the callus-cushions before their 
coalescence ; this is easily recognised by the brownish appearance of 
the tissues lying next to the peg and the interspersed groups of 
sclerotic cells. Owing to the pressure exerted by the fusing callus 
lips the arrangement of tissues is in this region much confused, 
groups of bark and wood elements being intermingled. 
The callus wood which has closed over the end of the embedded 
peg shows in a very marked degree the phenomenon known as 
“speckled” or “curled” grain. 1 The large medullary rays as seen 
in tangential section do not exhibit the usual narrow elliptical form 
hut are broadly oblong, triangular or circular in outline; while the 
course of the wood elements is much twisted (Plate II, Fig. 3). 
This peculiarity of structure is due in part to the jagged nature of 
the surface covered over by the callus and in part to the formation 
of adventitious buds, two of which are shown in transverse section 
in Plate II, Fig. 3. 
In six of the remaining seven wounds exhibited by the specimen 
the outer tissues alone have perished and healing by occlusion has 
resulted. The injuries occurred in the 50th, 61st, 63rd and 113th 
years of growth. The area of wood laid bare by these wounds 
varied in extent and the healing process occupied from two to five 
years according to the extent of the injury. In the largest wounds 
examined the exposed wood has undergone considerable decom¬ 
position, and fungus spores and mycelial threads were noticed. In 
other cases the exposed wood is perfectly sound and has been 
effectually protected against decay by the formation of tyloses and 
the impregnation of the walls with tannin. 
1 Frank. Krankheiten der Pflan?en, I, p. 80. 
