250 A. B. MACALLUM. 
and sulphide mixture gives in twenty-four hours a reaction 
like that represented in fig. 13 a, while in the slightly more 
developed structure the reaction is deeper with large dark- 
green granules (fig. 13 6). A similar result is obtained in 
the hyphe which terminate in two, three, or more pear-shaped 
outgrowths (fig. 12). In the hyphe below the fructification 
the cytoplasm is of a vesicular character, the walls of the 
vesicles being formed of an iron-holding substance, and as the 
terminal element develops, the vesicular character becomes 
less marked and the iron reaction less distinct, so that, finally, 
no iron may be found in this part of the filament. At the 
same time the granules in the fructification become more 
numerous, larger, and manifest a deep reaction for iron 
(fig 11). These granules are then found to be situated in 
small vesicles very much like the vesicles which, in hema- 
toxylin preparations, resemble nuclei. The granules revealed 
by the iron reaction are the same as those indicated by the 
hematoxylin stain. This is also true of the granules in the 
younger hyphe. The cytoplasm of the mycelial threads is, at 
this stage, free from ‘‘masked’’ compounds of iron, but in the 
earliest stages the mycelial threads give at once, on the applica- 
tion of the glycerine and sulphide mixture, a slight reaction for 
iron, which, however, becomes deeper at the end of twenty-four 
hours if heat be applied, this indicating the presence of 
“masked” iron. Granules in the cytoplasm along the course 
of the threads give a marked reaction for the metal like that 
manifested in the hyphe. It is probable that the absence of 
iron in the later stages of the threads may be due to the 
transference of the iron-holding compound to the hyphe. 
The question concerning the occurrence of nuclei in the 
Hymenomycetes has been dealt with by Strasburger,’ Rosen- 
vinge,? and Wager.? The two former describe them as obtain- 
1 ‘Das Botanische Practicum,’ pp. 380] and 4338, 1887. 
2 «Sur les noyaux des hyménomycétes,” ‘ Annales des Sciences Nat., Bot.,’ 
1886, Serie 7, vol. ili, p. 75. 
3. “On the Nuclei of the Hymenomycetes,” ‘Annals of Botany,’ 1892, 
vol. vi, p. 146. 
