The Biology of Polyporus Pargamenus Fries 163 
of the woody elements surrounding them. Oftentimes all the 
remaining contents of the cells, including starch grains, 
fungal hyphe that may have penetrated, etc., are covered 
with the same substance. From the manner of occurrence 
and distribution of the humic substance found in wood sur- 
rounding decayed areas of a trunk it would seem that this 
substance is formed as a by-product from the action of a 
fungus on the membranes of the woody substance, and that 
incidentally it is probably one of the products effective in 
preventing the unlimited spread and destructive action of 
the fungus. 
MEANS OF ENTRANCE AND RATE OF DECAY. 
The general occurrence of any given species of fungus 
over wide areas differing greatly in character, and the multi- 
tude of sporophores produced in any one locality, shows that 
spore formation and dissemination is of enormous magni- 
tude. Every sporophore produces, figuratively speaking, 
“millions” of spores, and each perfectly formed spore ecar- 
ries with it the possibilities of the formation of a new plant, 
provided that spore falls on a suitable substratum and meets 
with conditions suitable for growth. For their dissemina- 
tion the spores are dependent upon a great number of agen- 
cies, the most effective agency being wind which may carry 
these bodies for miles. Insects, especially the beetles, are 
also an aid in spore dissemination, since, after feeding on 
the sporophores, they escape bearing spores which they carry 
elsewhere. While innumerable spores are formed and dis- 
seminated — many chances thus being given for the develop- 
ment of new plants — the difficulty with which the spores 
germinate, owing to unfavorable natural conditions, is very 
great. Of the relatively small number of spores that actually 
succeed in falling on a suitable substratum and germinating 
thereon but few ever develop to mature plants owing to 
numerous adverse influences. Owing to the peculiar require- 
ments of the spore for germination and further develop- 
ment, hundreds or thousands usually fail to develop where 
