BLEMISHES IN SUGAR MAPLE. 
59 
exposure of the cambium. Figure 9B further shows the results 
of failure to close the hole in the bark and to cover the original 
wound, thus leaving the sapwood exposed and liable to increased 
staining. A cone of cambium and bast has formed over the bottom 
of the peck, which will persist permanently as a rounded protuber- 
ance and over which all succeeding wood layers will be molded. A 
condition similar to tins in a specimen having one layer of sapwood 
excavated is shown in the next figure (fig. 9C). The wound is not 
closed, the wood is left exposed, and if the healing has been com- 
pleted for the season, an inwardly projecting cone will be left as before 
which will affect the form of future annual rings. Figure 9D shows 
a specimen in which two rings of sapwood have been punctured and 
the next year's growth has been vigorous, rilling the original wound 
and pushing out into the hole in the bark. Succeeding wood layers 
0° J . 
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ET m 
«" 
1 
■ i 1 
■ 
3 
¥ 
B 
C 
D 
Fig. 9.— Effects of sapsucker work on wood of sugar maple {Acer saccharum). (From Hopkins.) 
would be bent outward over the protuberance which partly fills 
the wound. The conditions in wood which has made several years' 
growth since the original injuries is shown in figures 10A and 10B. 
Both illustrate specimens in which the sapwood was punctured and 
extensive staining has resulted. In one case vigorous growth fol- 
lowed the injury and the healing has taken place as in figure 9D, with 
the result that the annual layers of wood are bent outward over the 
wound. The other specimen gives evidence of weaker growth, only 
partly filling the original hole and not pushing out into the bark 
opening. Hence the more vigorous new bast pushed into the vacancy, 
forming a protuberance on the inner side of the bark, between which 
and the depression over the original wound the next layer was 
formed. In consequence the latter also was bent inward and so 
was every succeeding layer. 
