A study of the vesicular and tubular bodies observed in cells of Poria monticola was done with particular regard to their form, origin, and membrane structure. The membranes of lomasomes and pinocytotic vesicles display the sometimes asymmetric, distinctly trilaminar structure characteristic of the plasma membrane. Lomasomes are abundant and vary in appearance depending upon the method of fixation used. Nonlamellar associations of vesicles and short tubules probably represent the true structure of lomasomes in this organism. These lomasomes originate from the plasma membrane and do not appear to be associated exclusively with wall formation.