IRON COMPOUNDS IN ANIMAL AND VEGETABLE CELLS. 249 
toxylin. Further, there is a substance which constitutes cor- 
puscles of a nucleolar character in cells of this form, which 
stains with eosin and gives a marked reaction for iron, but 
differing from the chromatin substance in remaining unstained 
after treatment with hematoxylin. There is no nucleus, 
although such an organ may occur in other stages, especially 
in 8. Ludwigii.! 
When the mycelial threads and hyphe of Hyphelia ter- 
restris, Fries, are hardened in alcohol and stained with hema- 
toxylin, the cytoplasm generally is coloured, but it is specially 
affected by the stain in the terminal portions of the hyphe on 
which the elements of fructification are developing. One can 
find also, in such preparations, deeply-stained granules scattered 
in the cytoplasm of the hyphe, and at times also a vesicular 
cavity and a membrane enclosing these granules, which then 
simulate nucleoli. Sometimes such structures strongly re- 
semble nuclei, and mitotic conditions are suggested by the 
presence of pairs of rows of deeply-coloured granules placed 
opposite, and at avery short distance from, each other. In 
the fully-formed fructification these vesicular cavities and their 
deeply-stained granules may be most readily seen. Whether 
such structures are nuclei in the proper sense of the term it is 
difficult to say, but if they are, they contain only a small por- 
tion of what may be considered as the chromatin, which is 
diffused in the cytoplasm of the mycelial threads in the younger 
stages, but appears to be transferred to the hyphe when the 
fructification of the latter commences. When the latter stage 
is fully attained the mycelia and lower portions of the hyphz 
are found to have little or no cytoplasm and to stain very 
feebly, a result quite different from that obtained in the fructifi- 
cation. 
The distribution of the “ masked ” iron in this form is found 
to coincide very closely with the distribution of the stainable 
substance. In the simplest form of the hypha, the glycerine 
Ludwig (‘Lehrbuch der niederen Kryptogamen,’ 1892, p. 201) appears 
to regard S. Ludwigii as merely a stage in the development of Endomyces 
Magnuusii. 
