Some Observations on the Tumours on Veronica 
Chamaedrys caused by Sorosphaera Veronicae. 
BY 
JAMES E. BLOMFIELD, M.A., M.D. (Oxon.), 
AND 
E. J. SCHWARTZ, M.A., B.Sc., F.L.S., 
Demonstrator in Botany , King's College } London. 
With Plate V. 
% 
S OME time ago one of us found in his garden some irregular green 
swellings on the shoots of Veronica Chamaedrys ; a microscopical 
examination of a section revealed the presence of a parasite, the cells being 
filled with amoebiform organisms in various stages of development, the 
terminal stage being a spherical body in which the thick-coated spores 
surround a central cavity. 
The only reference that we could find to this organism was in 
Engler and Prantl’s ‘Die Natiirlichen PflanzenfamilienI. Teil, i Abth., 
p. 6, in which Schroter, who wrote the article on Phytomyxineae, recog¬ 
nizes the four genera, viz.: 
i. Plasmodiophora with free regularly formed spores; 
2. Phytomyxa with free irregularly shaped rod-like or angular spores; 
3. Tetramyxa with four spores enclosed in a delicate membrane ; 
4. Sorosphaera with many spores united in a hollow sphere. 
Schroter states that Sorosphaera is a parasite in the parenchymatous 
cells of living plants, that the spores are elliptical, united in large numbers 
into spherical balls and covered by a common membrane, and that the 
diameter of these balls varies from 15 /x to 20/x. 
He recognizes three host plants on which Sorosphaera is parasitic, 
viz. Veronica hederifolia , V. triphylla , and V. Chamaedrys . In these 
plants the parasite causes swellings or tumours, in the enlarged paren¬ 
chymatous cells of which are to be found the above-mentioned spherical 
balls. This being the only description we have been able to find of these 
tumours, we have made a further and more detailed study of them, the 
[Annals of Botany, Vol. XXIV. No. XCIII. January, 1910.] 
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