BIOLOGY OF ALEURODISCUS 
features the mitochondria described by Janssens agree with the cytoplasmic 
structures here described. GuiUiermond (10), in the first report of the 
occurrence of mitochondria in fungous tissues, had also described and 
figured a perinuclear aggregation of these structures in the ascus of 
Pustularia. 
At times the area of more densely aggregated granules is situated higher 
than the nucleus in the basidium or appears to be moving upward toward 
the apex of the basidium (fig. 23). 
When the basidium puts out sterigmata and forms spores, the granules 
appear in the cytoplasm of these structures (figs. 23, 28). In fact, they 
make it difficult to follow the nuclear phenomena here. In the spore at 
the left in figure 28, for instance, it is difficult to tell whether the spindle-like 
structure is a nuclear spindle or a group of the corpuscles gathered about 
the middle of a filament. 
The second type of structure, the filamentous form, occurs in both old 
and young basidia and spores and is occasionally seen in young growing 
hyphae and paraphyses. These filaments vary considerably in length and 
thickness, at times attaining a size so large as to appear like a foreign body 
thrust into the basidium. They are generally straight but may be curved, 
wavy, or slightly spiral. Occasionally two are seen lying parallel and 
closely approximated. They almost invariably extend in the direction of 
the long axes of the hyphae or basidia. The position occupied by one of 
the three shown in figure 22 is exceptional. Almost every basidium contains 
from one to four of these filaments. It is seldom that as many as six are 
encountered in the same basidium. 
The filaments are relatively strong, rigid structures. This is easily 
ascertained by a study of sections that were somewhat broken up in the 
course of preparation. Here the filaments are often seen projecting out of 
the end of a broken basidium and maintaining themselves in a rigid position. 
Several cases, too, were encountered in which a sterigma was broken loose 
and yet seemed held in place by the unbroken filament (fig. 24). 
There is a general tendency for the filaments to be directed toward the 
apex of the basidium, and when the sterigmata form, the filaments frequently 
extend into these structures. In fact it is quite common to see a filament 
extending from the basidium into the sterigma up to its apex. 
When the amount of acetic acid in the Flemming's solution is decreased 
the corpuscular bodies appear even more numerous, although they stand 
out less definitely than when Flemming's solution is used. This virtually 
gives Benda's solution used so extensively for mitochondrial fixation. Like- 
wise, Hermann's fluid gives equally good results. With Carnoy's and 
Zenker's fixatives the cytoplasm presents no structures in the finely granular 
ground work. These two latter solutions are strong in the amount of 
acetic acid. What is perhaps the best fixative for preserving the corpuscles 
and filaments consists of chrom-acetic to which formalin has been added. 
