154 LEVINE: CyTOLOGY OF HYMENOMYCETES 
The subhymenial cell from which the cystidium arises is pro- 
portionately larger and may be frequently traced back into a long 
filament of binucleated cells in the trama (PL. 5, FIG. 15). The cell 
wall is slightly thickened (PL. 6, FIG. 14) and is entirely covered by 
the mucilaginous material referred toabove. The evidence is clear 
that the cystidia, in B. granulatus at least, are glandular structures. 
The two nuclei are small in proportion to the volume of the cell 
but the nucleo-cytoplasmic equilibrium is not disturbed since the 
increase in the size of the cell is apparently due to an increase in 
the metaplasmic substances which form the source of the material 
that the cell excretes. The mucilaginous mass stains a faint orange 
with the triple stain. The outer surface of the gelatinous mass 
becomes dense and dark in color and ultimately forms a thin 
pellicle over the entire gland (PL. 7, FIG. 12). The formation of 
mucilage does not take place through any specialized pore as 
Massee (1887, 1904) holds, nor is it associated with any localized 
region of the cystidium as Maire (1910) and Knoll (1912) contend, 
but apparently takes place over the entire surface of the cystidial 
cell. Later the cystidium begins to disintegrate. Its cytoplasm 
shows large vacuoles. The nuclei also begin to show signs of 
disintegration. The nuclear membrane becomes faint, the 
nucleoles and chromatin lose their affinity for stains and soon 
disappear. Subsequent stages show the cell wall shriveled and the 
nuclei and cytoplasm entirely gone. Single flask-shaped cystidia 
(PL. 8, FIG. 60) are found in all the species of the Boleti I have 
studied except B. granulatus. Their nuclei and cytoplasm are 
essentially similar to those of B. granulatus. Tubular cystidia 
are found in B. vermiculosus, B. albellus, and B. scaber. They are 
long cylindrical binucleated cells filled with a granular cytoplasm 
similar to that described for B. granulatus. 
The nuclei of the basidia of the Boleti I have studied are quite 
favorable for cytological study. The chromatin strands stain 
blue and the nucleoles a bright ruby red, with the triple stain. 
The nucleoles have about the same size relative to that of the 
whole nucleus as they have in the higher plants. The cytoplasm 
of the young basidium (PL. 8, FIG. 46) is finely vacuolar and stains a 
faint orange. With the growth of the basidium the nuclei (PL. 6 
FIG. 16, 17) also increase in size. At the time of fusion their di- 
re. = a 
f: 
3) 
=. 
= 
Z 
