252 A. B. MACALLUM. 
glycerine and sulphide mixture, the application of heat to the 
preparation for a week will bring out appearances in the 
isolated elements like those represented in fig. 10. The most 
prominent feature in these is that the cytoplasm in both classes 
of structures contains “masked” iron. When the bodies 
regarded by Strasburger and Rosenvinge as nuclei were 
observed, they manifested a slightly deeper reaction for iron 
than the cytoplasm generally, but no structure was detected 
in them and they appeared as large granules rather than nuclei. 
The most marked reaction for iron was obtained in the spores 
in which a cytoplasmic reticulum was thus demonstrated. 
When, however, the spores are provided with a thick mem- 
brane, a reaction with the glycerine and sulphide mixture does 
not appear, but is obtained after the use of acid alcohols. As 
a rule, the reaction is uniform throughout the cytoplasm of 
the basidia. There are, however, constituents of the hymenium 
occasionally observed in which no iron was found. They 
possessed no sterigmata or spores, and from their association 
with the basidia I was inclined to regard them as paraphyses, 
but from the comparative scarcity of such elements free from, 
or poor in iron, they can scarcely be looked upon as belonging 
necessarily to that class, which in stained preparations is 
abundantly represented. The subhymenial cells also give a 
faint reaction for iron. 
It thus appears that in the leucosporous Hymenomycetes the 
cytoplasm of the hyphe in the early stages of the fungus con- 
tains iron, which is also present in the minute “‘ nuclei,” and 
that in later stages this cytoplasm gives a faint reaction or 
none at all for iron, while the cytoplasm of the basidia and 
spores contains enough “masked” iron to give a marked 
reaction. This distribution of the iron corresponds with the 
distribution of the stainable substance, and it may, therefore, 
be fairly concluded that the chromatin is here also iron- 
holding. 
In my earlier communication reference was made to the 
occurrence of an iron-containing substance in the gonidia of 
Cystopus candidus, and I stated that the iron compound 
