201 
Sections of such parts show that its mycelium is widespread in 
the wood and that it is more injurious than ordinarily supposed. 
The most destructive member of this family, however, is the honey- 
agaric, Armillaria mellea. Clusters of the yellow or brown fruit- 
bodies appear on old stumps and roots of trees, while the whitish 
or black strands of mycelium are abundant in wood attacked by 
ee species. These strands pass from one root to another be- 
neath the soil, causing their decay and the consequent death of 
in tree from starvation or its destruction by storms. 
Among the lower fungi attacking shade-trees, nectria is con- 
spicuous and important. The numerous, rounded, reddish-colored 
of water cut off. The very destructive chestnut-canker, Diaporthe 
parasitica, belongs to this class of diseases. Some species do 
not kill the limb entirely, but produce cancerous ines similar 
to those found on animals. The plane-tree disease is caused bya 
microscopic fungus, Gloeosporiuin nervisequum., living in the twigs 
and passing out along the nerves into the leaves as they expand, 
causing them to turn brown, become dry and fall. 
The leaves of trees are very often attacked by mildews, which 
spread over their surface, and by various spot-fungi, which cause 
areas of greater or less extent to decay. All of these forms 
withdraw food from the leaf and exhaust its energy, rendering it 
incapable of performing its proper functions and often causing its 
death. Leaves weakened by lack of food and air or punctured 
by mites are especially subject to attack. 
The proper care of the tree plantation consists in attending to 
the natural wants of the trees so far as soil, water and air are 
concerned ; in guarding them against mechanical injuries; in 
pruning them when necessary and in the proper manner ; and in 
protecting them against the ravages of insects and fungous dis- 
eases. When trees are otherwise properly cared . the attacks 
of fungi are usually much less frequent and less harmful. A 
diseased condition is often induced by starvation ; pan mechan- 
ical injury of any kind is often the first step towards decay. 
The entrance of fungi into the trunk of a tree is effected in 
many ways, chiefly through a wound of some kind. The bite 
