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 this 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, filling the original wound 

 and pushing out into the hole in the bark. Succeeding wood layers 





II 



J ' pff 



; I 



' El 



5 *"■'■ 



— ■ i" ■■": 



in 



'• 



\m 





tel 



1 i 







■ji 



^pj 





i 1 " 



1 n' I 





|'h 



i 



ABC D 



Fig. 9.— Eflects 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. 



