The Biology of Polyporus Pargamenus Fries 109 
verse section the individual cells of wood parenchyma resem- 
ble in general shape the fibrous elements, but have wider 
lumina by reason of their thinner walls. They predominate 
in the more porous parts of the growth rings and often closely 
surround the vessels. In the dense late wood, the wood 
parenchyma forms conspicuous, tangentially arranged bands 
alternating with irregular, compact rows of thick-walled wood 
fibers. Ona perfectly smooth transverse section havi ing well- 
defined late wood, these parenchyma bands can be detected 
with the unaided’ eye. When greatly mterrupted by wood 
fibers the parenchyma bands become indistinct and can be 
distinguished only by means of a microscope. 
Hie. 6. 
Bordered pit in butternut hickory (Hicoria 
minima) wood, transverse section, X 2,000. 
As seen in longitudinal section the wood parenchyma cells 
extend vertically in short rows, the terminal cells of which 
taper to a point. Structurally they resemble the pith-ray 
cells but have their long axes at right angles to these. The 
individual cells of wood parenchyma are mostly short and 
prismatic, their thin walls being furnished with ‘simple pits. 
Many of the individual cells contain solitary crystals of 
calcium oxalate belonging to the tetragonal ery stal system. 
These crystals are only slightly soluble even in the strongest 
acids and are readily seen under the high power of the micro- 
scope in all sections. In such eases the whole cell becomes 
