98 HEART-ROT 



of the traclicide. In this way many tracheides become 

 plugged by a moj-e or less consistent black mass, composed 

 of the disorganized walls and contents of the hy|)hae. In 

 slightly older patches the viscid black liquid in the centre 

 is absorbed by the surrounding hyphae, leaving only the 

 thin wliite delignified walls of the tracheides, pierced and 

 torn by iinnimerable bore-holes, and with scarcely sufficient 

 strength to maintain their structure. A touch is often 

 enough to tear them away, and then nothing is left but 

 a small hole in the wood. 



Sometimes it is found that by the side of a white patch 

 of delignified tracheides left by a black speck as described, 

 another black patch is foi-med, and in rare instances a l)lack 

 patch has been seen entirely surroimding a white one. By 

 this means holes which were originally small become large, 

 and eventually all the wood in an attacked region becomes 

 honeycombed. Black patches are also found in the middle 

 of white ones. How this occurs has not been determined, 

 but Hartig, who describes this state as typical, says that tlie 

 hj^pliae in a black patch delignify the tracheide ^^•alls 

 around them, though the black patch remains intact. 

 Wood that has become rotted in this way is dry, very light, 

 and has the colour of cork. It contains many holes and 

 white delignified patches, and almost always isome black 

 specks as well. 



The ultimate state of rotted wood is very varial)l(\ When 

 a trunk, or' more commonly a single rOot, is killed and 

 rotted right through to the cambium, the affected wood 

 dries as it rots, and becomes pale yellow, and at the same 

 time spongy and fibi'ous. On rubbing between tlie two 

 liands, it crumbles into a mass of fibres, which remain 

 more or less stringy and ai'e too weak to stand much strain. 

 Inside a trunk which has not been killed the gummy layer 

 prevents di'ying, so that the rot advances a stage farther. 

 The wood then resembles coarse sawdust of the consistency 

 of coco-nut fibre, sucii as is used for growing bulbs. Faiily 

 large pieces of v\ood may still lemain intact, though these 

 are always partly rotted and liddled with hoj'c-holes. 



