The Biology of Polyporus Pargamenus Fries iG!) 
oidia formation can continue indefinitely. Upon germina- 
tion, the oidia produce mycelium of the primary type, that 
18; mycelium lacking clamp connections (Plate XV and 
XVI). Falck (1902) cultivated a snerrnane number of 
the Agaricacew through the formation of oidia to the mature 
fructification and concluded that the oidium form is a defi- 
nite stage in the hfe-cycle of many of the higher fungi. 
Lyman (1907) shows that the production of oidia appears 
to be confined almost entirely to the higher families of the 
Ilymenomycetes, as was indicated by Brefeld (1889). 
Chlamydospores.— The formation of chlamydospores in 
Polyporus pargamenus agrees with the process in other 
groups of fungi. Any cell of the mycelium, under certain 
conditions, may form a chlamydospore; hence their position 
is either terminal or interealary. Cross-walls are not abun- 
dant in the vegetative mycelium of Polyporus pargamenus 
and chlamydospores are of only occasional occurrence. They 
may be formed either on superficial hyphze or on hyphee that 
have become submerged under the surface of the agar. In 
the process of their formation the protoplasm of the hypha 
becomes vacuolate, certain cells losing their contents entirely, 
while in others which are to produce chlamydospores the 
condensing protoplasm contracts away from the ends of the 
cell and concentrates in the middle region where the side 
walls become greatly distended to receive it (Plate XVII). 
Here a resistant wall (endospore) forms about the encysting 
cell within and adnate to the surrounding hypal walls, and 
cuts off the empty portion of the parent cell at each end. 
Continued contraction of the protoplasm may cause the 
abandonment of these end wails, and new walls may form 
farther in (Plate XVII, c). T he mature chlamydospore i is 
thick-walled with dense, granular, refractive contents which 
become vacuolate with age. As a general rule the terminal 
chlamydospores are pyriform while the interealary ones are 
more or less lemon-shaped, but great variation is exhibited 
owing to the different degrees of contraction of the proto- 
plasm. The mature spores are freed only by the decay of 
