Schwartz.—Parasitic Root Diseases of the Juncaceae . 517 
tion of the spores; unfortunately, I have not been successful in my attempts 
to germinate them. After the second of these mitoses each amoebula 
secretes for itself a wall which gradually thickens, and the amoebula is 
transformed into a spore; this wall, however, does not give any of the 
usual cellulose reactions, and probably contains chitin, a substance which, 
according to Wisselingh (6), is commonly to be met with in fungal cell-walls. 
The spores are wedge-shaped, with a single nucleus slightly nearer to the 
broader end ; this nucleus stains readily, and especially before the spore 
coat has thickened much ; in no case have I observed binucleate spores. 
These spores are either collected into sorospheres or loosely aggregated ; 
in either case they are usually enclosed by a common membrane, though 
this latter is sometimes absent, as, for instance, from the small groups of 
spores observed in root-hairs. A common form of spore arrangement 
consists of two rows filling a root-cell, the wedge-like shape of the spores 
lending itself to close packing. Various forms of sorospheres and spore 
collections are shown in Figs. 14 and ] 5. 
Structure of diseased roots. To the naked eye the roots of diseased 
plants show scarcely any indication of disease, save that they maybe slightly 
thinner and of a paler hue than those of uninfected plants, this latter 
distinction being perhaps due to the absence of starch. After some practice 
I was able to pick out roots in which the disease had advanced to the stage 
of sorosphere formation, but could only determine those with the earlier 
stages by microscopical examination. The infected cells are confined to 
the outer layers of the cortex ; these cells, however, are quite normal in size, 
nor do the roots themselves show any signs of hypertrophy. In the early 
stages, as shown in Fig. 1, the infected cells are filled with the cytoplasm 
and nuclei of the parasite ; frequently we have a single row of such nuclei, or 
at other times they form a double row in the root-cell. Rarely are to be 
found cells containing two or three separate amoebae. The infected cells 
themselves are never plurinucleate, as was so frequently the case in the 
hypertrophied cells of the Veronica and Brassica tumours, nor, as a rule, 
are the cell nuclei enlarged or degenerated to any extent. In later stages 
the cortical cells are to be seen filled with sorospheres or with loosely 
aggregated spores, as is shown in Figs. 11 and 14. The disease apparently 
does not penetrate deeply into the root, but is confined to the outer cortical 
layers ; as far as my observations go, the amoebae have no power of 
penetrating the cell-walls, a conclusion which is confirmed by the fact of the 
disease not spreading deeply into the root from the diseased outer portion 
of the cortex. As in the cases of the Veronica tumours and the clubbed 
roots of Cabbages, the stores of starch are largely depleted in the infected 
regions. The fact of there being no hypertrophy of the Juncus roots is of 
considerable interest, because it is contrary to the usual result of a plant 
becoming a prey to such a fungoid disease, e. g. P. Brassicae and 
