W. J. Dozvson. 
207 
ON A DISEASE OF GREENGAGE TREES CAUSED BY 
DERMATELLA PRUNASTRI PERS. 
By W. J. Dowson. 
[With Three Figures in the Text]. 
I.—Introduction. 
M Y investigation of this disease was made at the suggestion of 
Mr. F. T. Brooks, who had for some years past noticed it to 
be present in the greengage plantationsat Willingham and Cottenham 
near Cambridge. Little beyond the name and the distribution of 
this fungus was known and it was hoped that a thorough investigation 
of its life history in regard to its presence on greengages would be 
made. Unfortunately the work has been cut short owing to the 
fact of my leaving England; but as certain definite results have 
been obtained by investigation of the tissues of diseased branches 
and with pure cultures, it was thought worth while to record the 
work as far as it had gone. 
Inoculation experiments were made, but of too recent a date to 
allow of any detailed examination at the time of writing. One or 
two, however, were investigated, and the results are here given. 
I take this opportunity of expressing my sincere thanks to Mr. 
Brooks for his constant advice and criticism during the short time 
I have been able to devote to the work. My thanks are also due to 
Professor Seward who very kindly permitted me to carry on the 
investigation in the Botany School, Cambridge. 
The fungus has been described under the following names:— 
Peziza Prunastri Pers., Cenangium Pruncistri Fries, Dermatea 
Prunastri Fries, and Tympanis Prunastri Wallr. The conidial stage 
has been described as Sphceronema spurium (Fr.) Sacc. Saccardo 
refers to it as Cenangium Prunastri. Rabenhorst, referring to it as 
Derviatella Prunastri, considers the group genus Dermatea to be 
subdivided into three sub-genera of which Dermatella is the third, 
the others being Eudermatea and Pezizicula. Tubeuf and Engler 
and Prantl follow Rabenhorst’s classification in which the group 
genus Dermatea is placed in the family Cenangiacece of the order 
Pezizinece. Tubeuf in his “ Pflanzenkrankheiten ” mentions it as 
