16 College of Forestry 



The subject of pathologic heartwood formation received 

 additional light throiigii the investigation of the false heart 

 of red beech bj Ilartig and Weber (1888). Normally the 

 red l)eech does not form heartwood, even in old age. In 

 many cases, liowever, brown discolorations start from branch 

 wounds and. spread through the interior of the trunk, often 

 extending throughout its wliole length. In this reddish-brown 

 heart the vessels are occluded by tyloses and there are drops 

 of gum in tlie parenchyma cells and other elements. It is 

 stated that the increased entrance of air through the branch 

 wounds permits an increased activity of the living paren- 

 chyma cells. This is shown by the formation of tyloses and 

 wound gum in the parenchyma cells. It was observed that 

 fungal mycelium also occurs frequently in the dark brown 

 heart. The false heart is to be considered as pathologic and 

 does not differ essentially from genuine heart wood. 



Hermann (1902) confirmed the opinion of R. Hartig on 

 the origin of the false heartwood from branch wounds. He 

 also found fungal mycelium present in nearlj' all cases. The 

 false heartwood was considered as a protection by the tree 

 against the entrance of wood-destroying fungi into the 

 wounds. The fungal hypliae are at first occluded from air 

 and moisture by the tyloses and masses of gum, and their 

 development retarded. The tyloses and gum formations 

 ultimately are dissolved by the penetrating fungal hypae. 



Tuzson (1903) arrived at similar conclusions. He stated 

 that the tyloses and wound gum occur in the heartwood merely 

 in consequence of the stimulation by the fungus and not as a 

 reaction against the entrance of air after wounding. He 

 found that the red heartwood is more resistant to fungi than 

 the sapwood. The observation that a similar fonnation of 

 false heartwood also occurs in felled wood attacked by fungi 

 is important. Tuzson found that the formation of false 

 heart increases the specific gravity of the wood. 



Some work of Liudroth (1901), which is also based upon 



