16 
or whether the decayed areas were small, superficial and found 
on the larger limbs. The major decayed places were much more 
serious and impaired the value of the tree. 
n examination of the trees showed that 231 had decayed 
areas Classified as major, and 192 had decayed areas classified as 
minor. It is thus seen that 423 trees out of a total of 1,830, or 
about 23 per cent., were found to be injured by decay-producing 
fungi. Differences were noted among the various kinds of trees 
with reference to the occurrence of decay. Certain kinds of trees, 
as the silver maple, the Norway maple, the ashes, and the birches, 
showed a very high percentage of decayed areas. In these cases 
25 to 50 per cent. of the trees were more or less injured by decay- 
producing organisms. Many of the different varieties of trees, 
however, showed much lower percentages of injury. 
In very few cases were collections made of the fruiting bodies 
of the fungi responsible for the decay. This was due, in part 
at least, to the fact that these structures are rather conspicuous 
and thus attract the attention of individuals who remove them 
from the trees. Further, the pruning operations carried out by 
the Park workmen tend to the removal of these fungous struc- 
tures. It is also known that wood-destroying fungi may be 
present for many years without producing their fruiting stages. 
The mycelium, however, continues to develop and to cause ex- 
tensive decay of the wood. 
In several cases, however, the fruiting structures of various 
polypores were secured. Several specimens of Polyporus betuli- 
nus (Bull.) Fr. were obtained from the gray birch. The trees 
were severely injured by the growth of this fungus, the larger 
limbs being almost completely destroyed through its action. 
A well-developed specimen of Daedalea quercina (L.) Pers. 
was found on the English oak. The fruiting body was located 
at a point on one of the large limbs where, previously, a smaller 
limb had been pruned off. The fungus had doubtless gained en- 
trance at the pruned surface and, by subsequent growth, had pro- 
duced decay back for a considerable distance. In fact, the de- 
cayed region extended back almost to the main trunk of the tree. 
A specimen of Fomes applanatus (Pers.) Wallr. was collected 
on the honey locust. It was found near the base of the tree, 
