The Biology of Polyporus Pargamenus Fries 61 
the layer of basidia with their spores. As Overholts (1915, 
pp. 684-685) states, in Polyporus pargamenus the pres- 
ence of cystidia is a variable character, and that they are 
abundant in some specimens but very scarce in others. In 
such eases he recommends the making of longitudinal sec- 
tions of the tubes as the eystidia are sometimes more abun- 
dant in one part of the tubes than another. 
The ecystidia resemble the basidia in shape but are con- 
sider: ably larger and longer, sometimes reaching a length of 
twenty microns and a breadth of six microns, as stated by 
Overholts (1915, p. 685). They are further characterized 
by being distinctly capitate — probably with minute crystals 
of calcium oxalate although no crystalline structure is visi- 
ble even under the highest power of the microscope (Fig. 1). 
These colorless cystidia are rendered very conspicuous by 
reason of their capitate tips. Sometimes they scarcely extend 
beyond the basidia, although they usually project sufficiently 
far that one can distinguish them re: adily with the low power 
of the microscope. In the sections examined none of the 
evstidia projected more than ten microns beyond the sterig- 
mata of the basidia. 
Spore Characters.— The sporphores of Polyporus parga- 
menus were found to begin the production of spores even 
before they measured as much as 1 em. in either dimension, 
and to continue to shed viable spores intermittently until 
old age. When a fresh sporophore is placed on a glass slide 
or paper the falling spores rapidly accumulate and a plen- 
tiful supply is obtained within a few hours. The spores may 
be seen to best advantage macroscopically on black paper, 
where the numerous little white heaps look hke an imprint 
of the hymenial surface of the sporophore. Owing to their 
pronounced adhesiveness they adhere to one another and to 
any surface with which they come into contact with consider- 
able tenacity. Spore-deposits, therefore, cannot be shaken 
off paper or glass upon which they have collected. In fact 
they adhere so tenaciously that, when shed upon g glass and 
- dried, they can be scraped off as ribbons 4 or 5 mm. long. 
