98 HEART-ROT 
of the tracheide. In this way many tracheides become 
plugged by a more or less consistent black mass, composed 
of the disorganized walls and contents of the hyphae. In 
slightly older patches the viscid black liquid in the centre 
is absorbed by the surrounding hyphae, leaving only the 
thin white delignified walls of the tracheides, pierced and 
torn by innumerable 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 formed, and in rare instances a black 
patch has been seen entirely surrounding 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 the 
hyphae in a black patch delignify the tracheide walls 
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 some black 
specks as well. 
The ultimate state of rotted wood is very variable. 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 fibrous. On rubbing between the two 
hands, it crumbles into a mass of fibres, which remain 
more or less stringy and are too weak to stand much strain. 
Inside a trunk which has not been killed the gummy layer 
prevents drying, so that the rot advances a stage farther. 
The wood then resembles coarse sawdust of the consistency 
of coco-nut fibre, such as is used for growing bulbs. Fairly 
large pieces of wood may still remain intact, though these 
are always partly rotted and riddled with bore-holes, 
