The Biology of Polyporus Pargamenus Fries 189 
to be non-specialized and secures its nutrient substances from 
the easiest available source. 
Germination of the basidiospores occurs regularly in a 
great number of nutrient media, but the percentage of ger- 
mination and subsequent growth of the mycelium is directly 
proportional to the suitability of the culture medium used. 
Germination also occurs in both tap and distilled water, thus 
showing that an external food supply is not necessary for the 
germination of the spores, although it greatly accelerates it. 
Germination was not stimulated, but was greatly retarded, 
by the use of slight quantities of alcohol and ether. In their 
germination the spores exhibited no especial preference for 
either acid or alkaline nutrient media. 
The change in the mycelium from the short-lived primary 
mycelium, which is the product of the elongating germ tubes, 
to the typical secondary mycelium apparently is a regular 
occurrence not influenced by the nature of the culture 
medium or by other external factors. 
The occurrence of two secondary spore forms, namely oidia 
and chlamydospores, as definite stages in the life cycle of this 
plant is here reported for the first time. Oidia were ob- 
served to form repeatedly on both primary and secondary 
mycelium; chlamydospores, however, were observed to form 
only on the secondary mycelium. The formation of oidia 
apparently can continue indefinitely or at least for several 
successive generations. 
The basidiosporic hymenium has been developed from the 
basidiospore in petri dish cultures on nutrient agar, and also 
from the mycelium contained in a bit of birch bark when 
inoculated on sterile blocks of wood, thus completing the life- 
eycle of this fungus. 
The decay of wood by Polyporus pargamenus consists of 
a series of chemical and physical changes brought about by 
the reduction of the woody substance by enzyme secretions 
of the vegetative mycelium. The dissolution of the cell-walls 
is to be attributed to the fact that they, as a potential source 
of food, are valueless to the fungus until broken down and 
reduced te a condition suitable for translocation and assimi- 
lation. 
