208 
W. /. Dowson. 
parasitic upon various varieties of plums; as does also Sorauer who 
in his “Handbuch der Pflanzenkrankheiten ” (Bd. II, 1906), refers 
to it as Dermatea prunastri. 
II.— Culture Media. 
Agar-agar was used throughout to stiffen decoctions of Victoria- 
plum wood, greengage wood, and grape juice. All three media 
were just slightly acid. Sterilised blocks (30x16x6 mm.) of 
greengage wood and sterilised pieces of bark of the same were also 
employed. 
III. —Field Observations. 
Among the greengage and victoria plum plantations w'hich are 
to be found in the neighbourhood of Cambridge, the fructifications 
of Dermcitella prunastri have been recently noticed upon some of the 
dead branches of both young and old trees. The greengages were 
chiefly attacked, but the Dermatella has also been found once upon 
a Gioborne plum. The diseased branches and twigs were evidently 
affected with some sort of “ die back,” and it was thought likely 
that the association of Dermatella prunastri with the “ die back ” 
condition was more than accidental. Several expeditions were 
made in the autumn of 1912 to Willingham where certain fruit 
plantations contain large numbers of greengage trees. 
The dead branches were easily distinguished from healthy ones 
by the fact that they were covered with Pleurococcus sp. and lichens, 
whereas the healthy branches and shoots were fairly clean. Branches 
of various ages showed signs of attack, and ranged from twigs of a 
few years growth to old branches as thick as a man’s wrist. Some 
portion of these dead branches bore the fructifications of Dermatella, 
and these were generally the distal parts which were covered fairly 
completely with the pycnidia and apothecia of the fungus (Fig. 1). 
Sometimes these were observed towards the proximal end of the 
branch, either in large groups or in smaller patches scattered 
irregularly over the whole branch. Occasionally the fructifications 
were seen on the bark of a trunk. The bases of some branches 
which were quite dead bore fructifications, but in others in which 
the basal part was apparently unaffected the fruit bodies were 
situated at some distance from the junction between the diseased 
and healthy tissues. I use the word “apparently” advisedly because 
the line of demarcation as seen in the cortex and older wood does 
not always coincide with the junction in the interior of a branch. 
