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HARVEY E. STORK 
sterigmata are usually seen. To some extent, the age of a basidium can be 
ascertained from this elevation above the surface. Another check on the 
degree of advancement of the nuclear divisions is the length of the sterigmata 
and the size of the primordial spore vesicles. The two divisions of the 
fusion nucleus are completed when the sterigmata begin to form (fig. 23, 
PI. XXXIII). The nest of four daughter nuclei rests for a relatively long 
time while the sterigmata are elongating and the spores are developing. 
The young hyphae and the paraphyses in the hymenium are always 
binucleate (figs. 17, 18). The nuclei in the primordial basidial cell fuse 
quite early, even before the basidia have begun to enlarge to any great 
extent. The fusion nucleus can be easily recognized by its relatively large 
size, its elongated shape, and especially by the character of the chromatin 
material (figs. 19, 20). This remains in the form of a spireme throughout 
the period of the growth of the nucleus until the first nuclear division. It 
seems that there are many more basidia formed than ever come to sporula- 
tion. The upper part of the hymenium is crowded as a result of the large 
size of the sporulating basidia, and many smaller ones are left below, lacking 
room for further development. 
Cytoplasmic Structure 
The cytoplasm of the hyphae and especially of the basidia presents 
some very striking appearances when fixed in Flemming's medium solution 
and stained with haematoxylin. In the young, actively growing hyphae and 
in the basidia, it consists of a finely granular ground substance in which 
are embedded larger elements. These larger elements occur in two forms. 
The most abundant form is that of round or somewhat elongated corpuscles 
varying in size from minute granules to relatively large bodies reaching i 11 
in diameter. Less abundant is the second form, which consists of long 
filaments that may attain a length of 40 or more. Both types of structures 
present the same appearance under different kinds of staining, and an 
examination of the preparations leads one to conclude that they are the 
same kind of substance differing only in form. 
The corpuscular forms appear most strikingly in the basidia, for here 
they are more abundant and often of larger size than in the other elements. 
They are not distributed uniformly throughout the cytoplasm. The 
tendency is for them to be most numerous in the upper part of the basidia 
while in the lower part of the basidia they are usually of somewhat larger 
size though fewer in number. In many cases they are aggregated about 
the fusion nucleus of the basidium so as to obscure the detail of the nuclear 
structures, and this aggregation is usually seen in the upper part of the 
nucleus so as to give the appearance of a sort of cap (fig. 21). In this 
connection we are reminded of the description and figures presented by 
Janssens et al. (12) of the mitochondria in the young ascus. They speak of 
them as forming a cap on one side of the nucleus. In a number of other 
