514 Schwartz.—Parasitic Root Diseases of the Juncaceae. 
out portions thereof were mounted, and served as well as sections ; indeed, 
they showed the root-hairs to better advantage than the sections did. 
SOROSPHAERA JUNCI. 
Whilst examining microscopically a piece of the root of a plant of 
J. articulatus for the purpose of ascertaining whether the hyphae or spores 
of the Entorhiza were present in it, I was surprised and interested in 
discovering certain spherical balls, which, consisting as they did of 
a series of wedge-shaped spores surrounding a central cavity, reminded 
me forcibly of the sorospheres of the terminal phase of Sorosphaera 
Veronicae; the shape of these sorospheres was, however, not always 
spherical, but more frequently ellipsoidal, and at times they appeared as 
merely loosely aggregated masses of spores filling the root-cells ; in size, 
too, the spherical sorospheres were mostly smaller than those found in 
Veronica tumours. A more extended search revealed the presence of 
plurinucleate amoebiform organisms in some of the root-cells of the younger 
roots, which convinced me that the roots were attacked by a Mycetozoan 
parasite allied to the S. Veronicae , whose life-history I had recently studied. 
This opinion was strengthened and confirmed by observing the presence of 
numerous oil-drops in the infected cells. 
As the life-history of the parasite closely follows that of Plasmodio- 
phora Brassicae and Sorosphaera Veronicae , it may, as in their case, be 
divided into stages, viz. the vegetative or schizont and the reproductive or 
sporont, each of these stages being characterized by its nuclei, and these 
two stages being separated by an intervening phase known as the akaryote 
or chromidial stage. 
Mode of infection. The earliest stage I have observed of the Soro¬ 
sphaera as a parasite in the root of a Juncus plant consisted in the 
presence of a small plurinucleate amoeba, having six nuclei, in one of the 
root-hairs of a young root of J. articulatus. Each of these nuclei had 
a large nucleolus, or karyosome, and was surrounded by a definite nuclear 
membrane, with granules of chromatin at the periphery; the cytoplasm of 
the amoeba was of the usual granular type, and minute drops of oil were 
found to be contained in it. An illustration of this infected root-hair is 
given in PL XL, Fig. 10. A microscopical examination of the root-hairs 
showed that they formed one means by which the parasite gained an entrance 
into the root, as amoebae in various stages of development were to be seen in 
them. Part of one such hair filled with the protoplasm and numerous nuclei 
of the parasite—many of them in an active stage of division—is shown in 
Ph’g. 5 ; a portion of a similar root-hair obtained from a plant uprooted in the ' 
late autumn after the onset of frost is represented in Fig. 13, where it is 
shown filled with the spores of the Sorosphaera. It is probable that the 
actual infection is effected by the entry of a mononucleate amoeba into 
