518 Schwartz.—Parasitic Root Diseases of the Juncaceae. 
S. Veronicae. It is the more strange from the fact that the Juncus roots 
form tubercles or nodules in response to the stimulus of the parasitic 
Entorhiza and also the abnormal stem and leaf structures when attacked by 
the mite ‘ Livia Juncorum This freedom from hypertrophy may probably 
be accounted for by the superficial situation of the disease contrasted with 
the more deeply-seated cambial infection found in Veronica. With but 
one exception, I have never found any trace of the Sorosphaera in the 
tubercles caused by the Entorhiza , nor indeed on the actual roots bearing 
these tubercles. In the course of my investigations I have met with plants 
attacked simultaneously by all three diseases, viz. the Entorhiza , the Soro- 
sphaera , and the Livia , and still to all appearance healthy and capable of 
giving rise to vegetative offspring by rooting at the joints of their prostrate 
stems ; in these instances such of the roots as remain healthy are sufficient 
for the needs of the plants. Of the three diseases—the club-root of 
Cabbage, the Veronica tumours, and the S. Junci —the first is the most 
destructive, as, by attacking the tap-root in addition to weakening the 
plant by the formation of the large club, or tumour, the adequate supply 
of soil water to the plant is intercepted, and in hot weather wilting ensues. 
In the Veronica plants no such destruction occurs, and as the stem only is 
affected, a minimum amount of harm is done to the plant, which usually 
possesses other healthy stems. In the present case the J uncus plant 
possesses a number of fibrous roots and not a main or tap-root, so that if 
a few of its roots become diseased, it probably still has or forms a sufficient 
number of healthy ones for its needs. In all three instances harm results 
to the plant, this being evidenced by the considerable depletion of starch 
which occurs. I see no reason to describe the relationship between the 
fungus and the plant at any stage of the disease otherwise than that 
of parasite and host, although with reference to the early stages of Brassica 
tumours it has been spoken of as a symbiotic relationship. 
Systematic position and affinities of Sorosphaera Junci. Maire and 
Tison, following Schroter’s classification in their paper on the Plasmodio- 
phoraceae (= Phytomyxineae, Schroter), divide them into the three following 
genera:—• 
1. Plasmodiophora , Wor. Sporont giving rise to free spores. 
2. Sorosphaera , Schrot. Sporont giving rise to spores collected into 
spherical balls. 
3. Tetramyxa , Goebel. Sporont giving rise to spores in tetrads. 
Schroter had included a fourth genus, Phytomyxa , with free, rod-shaped 
spores; this was represented by the organism which is now known as 
Pseudomonas radicicola , the bacterium of the leguminous root-tubercles. It 
is obvious that the parasite of the J uncus roots should be classed with the 
genus Sorosphaera , for the wedge-shaped spores are to be found collected 
