THALLOPHYTES 
8 9 
so into the basidiospores, have all been observed in mushrooms. In the common 
field mushroom (Agaricus campestris) the basidium often produces only two 
sterigmata and spores, but in such 
cases four nuclei have been ob- 
served in the mature basidium. 
The vegetative mycelium has been 
observed to be binucleate, the con- 
dition found in the uredospore- 
teleutospore mycelium of rusts. 
With a uninucleate basidiospore 
and a binucleate mycelium, it is a 
matter of interest to determine 
where the binucleate condition 
originates. It is suggested that 
the basidiospore upon germination 
becomes binucleate. In that case, 
if the interpretation applied to the 
rusts (see p. 84) obtains among 
the mushrooms, the mycelium with 
its sporophore is the sporophyte, 
and the basidiospore represents 
the gametophyte. 
2. Gasteromycetes 
These are the most highly 
FIG. 200. Coprinus : section of under side 
of pileus, showing section of the stipe in the cen- 
ter, and the radiating (sometimes branching) gills 
coated by the hymenium. 
organized of the fungi, the complexity appearing in the structure of 
the sporophore. The hymenium is inclosed within the sporophore, 
which opens only after the spores 
are mature. The sporophore is 
differentiated into an outer zone 
of cortical hyphae (peridiwri) and 
an inner mass of tissue (gleba) 
which contains the numerous ba- 
sidium-bearing chambers. These 
chambers either are filled with 
loosely woven hyphae whose lat- 
eral branches terminate in basidia, 
or are lined by a definite hyme- 
FIG. 201. Coprinus: section of the nial layer. The gradually increas- 
hymenium, showing basidia bearing basidio- ing complexity of the sporophore 
spores; the curving of the basidia makes it w ; n be observe d in the following 
impossible to show their actual connections 
in a section. groups: 
